CSP: Support for "LoadInfo::GetLoadingContext" and "LoadInfo::GetLoadingContextXPCOM()"

https://bugzilla.mozilla.org/show_bug.cgi?id=1439713 (partially)

netwerk/base/nsILoadInfo.idl

@@ -10,7 +10,7 @@
 interface nsIDOMDocument;
 interface nsINode;
 interface nsIPrincipal;
-
+native LoadContextRef(already_AddRefed<nsISupports>);
 %{C++
 #include "nsTArray.h"
 #include "mozilla/BasePrincipal.h"
@@ -333,6 +333,21 @@ interface nsILoadInfo : nsISupports
   [noscript, notxpcom, nostdcall, binaryname(ContextForTopLevelLoad)]
   nsISupports binaryContextForTopLevelLoad();
 
+  /**
+   * For all loads except loads of TYPE_DOCUMENT, the loadingContext
+   * simply returns the loadingNode. For loads of TYPE_DOCUMENT this
+   * will return the context available for top-level loads which
+   * do not have a loadingNode.
+   */
+  [binaryname(LoadingContextXPCOM)]
+  readonly attribute nsISupports loadingContext;
+  
+  /**
+   * A C++ friendly version of the loadingContext.
+   */
+  [noscript, notxpcom, nostdcall, binaryname(GetLoadingContext)]
+  LoadContextRef binaryGetLoadingContext();
+
   /**
    * The securityFlags of that channel.
    */