Issue #618 - (async) Implement async attribute for inline module scripts.

This commit does several things:
- Moves the pref check from ScriptLoader to ns[I]Document so it can be called on
the document.
- Changes the atrribute freezing function to a better name that takes the
document as a parameter.
- Sets the proper async/defer attributes on HTML script elements based on
keywords and whether they are module scripts or not.

dom/base/nsDocument.cpp

@@ -12446,3 +12446,16 @@ nsIDocument::GetSelection(ErrorResult& aRv)
 
   return nsGlobalWindow::Cast(window)->GetSelection(aRv);
 }
+
+bool
+nsIDocument::ModuleScriptsEnabled()
+{
+  static bool sEnabledForContent = false;
+  static bool sCachedPref = false;
+  if (!sCachedPref) {
+    sCachedPref = true;
+    Preferences::AddBoolVarCache(&sEnabledForContent, "dom.moduleScripts.enabled", false);
+  }
+
+  return nsContentUtils::IsChromeDoc(this) || sEnabledForContent;
+}

dom/base/nsIDocument.h

@@ -2851,6 +2851,8 @@ public:
     return mIsWebComponentsEnabled;
   }
 
+  bool ModuleScriptsEnabled();
+
 protected:
   bool GetUseCounter(mozilla::UseCounter aUseCounter)
   {

dom/html/HTMLScriptElement.cpp

@@ -280,12 +280,20 @@ HTMLScriptElement::GetScriptCharset(nsAString& charset)
 }
 
 void
-HTMLScriptElement::FreezeUriAsyncDefer()
+HTMLScriptElement::FreezeExecutionAttrs(nsIDocument* aOwnerDoc)
 {
   if (mFrozen) {
     return;
   }
 
+  MOZ_ASSERT(!mIsModule && !mAsync && !mDefer && !mExternal);
+
+  // Determine whether this is a classic script or a module script.
+  nsAutoString type;
+  GetScriptType(type);
+  mIsModule = aOwnerDoc->ModuleScriptsEnabled() &&
+              !type.IsEmpty() && type.LowerCaseEqualsASCII("module");
+
   // variation of this code in nsSVGScriptElement - check if changes
   // need to be transfered when modifying.  Note that we don't use GetSrc here
   // because it will return the base URL when the attr value is "".
@@ -300,14 +308,13 @@ HTMLScriptElement::FreezeUriAsyncDefer()
 
     // At this point mUri will be null for invalid URLs.
     mExternal = true;
-
-    bool defer, async;
-    GetAsync(&async);
-    GetDefer(&defer);
-
-    mDefer = !async && defer;
-    mAsync = async;
   }
+  
+  bool defer, async;
+  GetAsync(&async);
+  mAsync = (mExternal || mIsModule) && async;
+  GetDefer(&defer);
+  mDefer = mExternal && !async && defer;
 
   mFrozen = true;
 }

dom/html/HTMLScriptElement.h

@@ -41,7 +41,7 @@ public:
   virtual bool GetScriptType(nsAString& type) override;
   virtual void GetScriptText(nsAString& text) override;
   virtual void GetScriptCharset(nsAString& charset) override;
-  virtual void FreezeUriAsyncDefer() override;
+  virtual void FreezeExecutionAttrs(nsIDocument* aOwnerDoc) override;
   virtual CORSMode GetCORSMode() const override;
 
   // nsIContent

dom/script/ScriptElement.cpp

@@ -128,11 +128,11 @@ ScriptElement::MaybeProcessScript()
     return false;
   }
 
-  FreezeUriAsyncDefer();
+  nsIDocument* ownerDoc = cont->OwnerDoc();
+  FreezeExecutionAttrs(ownerDoc);
 
   mAlreadyStarted = true;
 
-  nsIDocument* ownerDoc = cont->OwnerDoc();
   nsCOMPtr<nsIParser> parser = ((nsIScriptElement*) this)->GetCreatorParser();
   if (parser) {
     nsCOMPtr<nsIContentSink> sink = parser->GetContentSink();

dom/script/ScriptLoader.cpp

@@ -390,19 +390,6 @@ ScriptLoader::CheckContentPolicy(nsIDocument* aDocument,
   return NS_OK;
 }
 
-bool
-ScriptLoader::ModuleScriptsEnabled()
-{
-  static bool sEnabledForContent = false;
-  static bool sCachedPref = false;
-  if (!sCachedPref) {
-    sCachedPref = true;
-    Preferences::AddBoolVarCache(&sEnabledForContent, "dom.moduleScripts.enabled", false);
-  }
-
-  return nsContentUtils::IsChromeDoc(mDocument) || sEnabledForContent;
-}
-
 bool
 ScriptLoader::ModuleMapContainsURL(nsIURI* aURL) const
 {
@@ -1227,14 +1214,12 @@ ScriptLoader::ProcessScriptElement(nsIScriptElement *aElement)
 
   nsCOMPtr<nsIContent> scriptContent = do_QueryInterface(aElement);
 
-  // Determine whether this is a classic script or a module script.
   nsAutoString type;
   bool hasType = aElement->GetScriptType(type);
-  ScriptKind scriptKind = ScriptKind::Classic;
-  if (ModuleScriptsEnabled() &&
-      !type.IsEmpty() && type.LowerCaseEqualsASCII("module")) {
-    scriptKind = ScriptKind::Module;
-  }
+
+  ScriptKind scriptKind = aElement->GetScriptIsModule() ?
+                          ScriptKind::Module :
+                          ScriptKind::Classic;
 
   // Step 13. Check that the script is not an eventhandler
   if (IsScriptEventHandler(scriptKind, scriptContent)) {
@@ -1268,7 +1253,7 @@ ScriptLoader::ProcessScriptElement(nsIScriptElement *aElement)
   // the nomodule attribute will be ignored".
   // "The nomodule attribute must not be specified on module scripts (and will
   // be ignored if it is)."
-  if (ModuleScriptsEnabled() &&
+  if (mDocument->ModuleScriptsEnabled() &&
       scriptKind == ScriptKind::Classic &&
       scriptContent->IsHTMLElement() &&
       scriptContent->HasAttr(kNameSpaceID_None, nsGkAtoms::nomodule)) {
@@ -1480,6 +1465,12 @@ ScriptLoader::ProcessScriptElement(nsIScriptElement *aElement)
   request->mIsInline = true;
   request->mLineNo = aElement->GetScriptLineNumber();
 
+  // Only the 'async' attribute is heeded on an inline module script and
+  // inline classic scripts ignore both these attributes.
+  MOZ_ASSERT(!aElement->GetScriptDeferred());
+  MOZ_ASSERT_IF(!request->IsModuleRequest(), !aElement->GetScriptAsync());
+  request->SetScriptMode(false, aElement->GetScriptAsync());
+
   if (request->IsModuleRequest()) {
     ModuleLoadRequest* modReq = request->AsModuleRequest();
     modReq->mBaseURL = mDocument->GetDocBaseURI();
@@ -2601,7 +2592,7 @@ ScriptLoader::PreloadURI(nsIURI *aURI, const nsAString &aCharset,
   }
 
   // TODO: Preload module scripts.
-  if (ModuleScriptsEnabled() && aType.LowerCaseEqualsASCII("module")) {
+  if (mDocument->ModuleScriptsEnabled() && aType.LowerCaseEqualsASCII("module")) {
     return;
   }
 

dom/script/ScriptLoader.h

@@ -606,8 +606,6 @@ private:
   JS::SourceBufferHolder GetScriptSource(ScriptLoadRequest* aRequest,
                                          nsAutoString& inlineData);
 
-  bool ModuleScriptsEnabled();
-
   void SetModuleFetchStarted(ModuleLoadRequest *aRequest);
   void SetModuleFetchFinishedAndResumeWaitingRequests(ModuleLoadRequest *aRequest,
                                                       nsresult aResult);

dom/script/nsIScriptElement.h

@@ -13,6 +13,7 @@
 #include "nsIScriptLoaderObserver.h"
 #include "nsWeakPtr.h"
 #include "nsIParser.h"
+#include "nsIDocument.h"
 #include "nsContentCreatorFunctions.h"
 #include "nsIDOMHTMLScriptElement.h"
 #include "mozilla/CORSMode.h"
@@ -37,6 +38,7 @@ public:
       mForceAsync(aFromParser == mozilla::dom::NOT_FROM_PARSER ||
                   aFromParser == mozilla::dom::FROM_PARSER_FRAGMENT),
       mFrozen(false),
+      mIsModule(false),
       mDefer(false),
       mAsync(false),
       mExternal(false),
@@ -73,11 +75,25 @@ public:
   virtual void GetScriptCharset(nsAString& charset) = 0;
 
   /**
-   * Freezes the return values of GetScriptDeferred(), GetScriptAsync() and
-   * GetScriptURI() so that subsequent modifications to the attributes don't
-   * change execution behavior.
+   * Freezes the return values of the following methods so that subsequent
+   * modifications to the attributes don't change execution behavior:
+   *  - GetScriptIsModule()
+   *  - GetScriptDeferred()
+   *  - GetScriptAsync()
+   *  - GetScriptURI()
+   *  - GetScriptExternal()
    */
-  virtual void FreezeUriAsyncDefer() = 0;
+  virtual void FreezeExecutionAttrs(nsIDocument* aOwnerDoc) = 0;
+
+  /**
+   * Is the script a module script?
+   * Currently only supported by HTML scripts.
+   */
+  bool GetScriptIsModule()
+  {
+    NS_PRECONDITION(mFrozen, "Execution attributes not yet frozen: Not ready for this call!");
+    return mIsModule;
+  }
 
   /**
    * Is the script deferred. Currently only supported by HTML scripts.
@@ -292,6 +308,11 @@ protected:
    */
   bool mFrozen;
 
+  /**
+   * The effective moduleness.
+   */
+  bool mIsModule;
+
   /**
    * The effective deferredness.
    */

dom/svg/SVGScriptElement.cpp

@@ -137,7 +137,7 @@ SVGScriptElement::GetScriptCharset(nsAString& charset)
 }
 
 void
-SVGScriptElement::FreezeUriAsyncDefer()
+SVGScriptElement::FreezeExecutionAttrs(nsIDocument* aOwnerDoc)
 {
   if (mFrozen) {
     return;

dom/svg/SVGScriptElement.h

@@ -44,7 +44,7 @@ public:
   virtual bool GetScriptType(nsAString& type) override;
   virtual void GetScriptText(nsAString& text) override;
   virtual void GetScriptCharset(nsAString& charset) override;
-  virtual void FreezeUriAsyncDefer() override;
+  virtual void FreezeExecutionAttrs(nsIDocument* aOwnerDoc) override;
   virtual CORSMode GetCORSMode() const override;
 
   // ScriptElement

parser/html/nsHtml5TreeOperation.cpp

@@ -1076,7 +1076,7 @@ nsHtml5TreeOperation::Perform(nsHtml5TreeOpExecutor* aBuilder,
       nsCOMPtr<nsIScriptElement> sele = do_QueryInterface(node);
       NS_ASSERTION(sele, "Node didn't QI to script.");
       sele->SetScriptLineNumber(mFour.integer);
-      sele->FreezeUriAsyncDefer();
+      sele->FreezeExecutionAttrs(node->OwnerDoc());
       return NS_OK;
     }
     case eTreeOpSvgLoad: {