Bug 1330900 - Implement <script nomodule>

This patch implements:
- noModule getter/setter for HTMLScriptElement
- the nomodule attribute for HTMLScriptElement
- the logic in nsScriptLoader that denies the loading of a nomodule script
- tests

Tag #618

dom/html/test/file_script_module.html

@@ -0,0 +1,42 @@
+<html>
+<body>
+  <script>
+// Helper methods.
+function ok(a, msg) {
+  parent.postMessage({ check: !!a, msg }, "*")
+}
+
+function is(a, b, msg) {
+  ok(a === b, msg);
+}
+
+function finish() {
+  parent.postMessage({ done: true }, "*");
+}
+  </script>
+
+  <script id="a" nomodule>42</script>
+  <script id="b">42</script>
+  <script>
+// Let's test the behavior of nomodule attribute and noModule getter/setter.
+var a = document.getElementById("a");
+is(a.noModule, true, "HTMLScriptElement with nomodule attribute has noModule set to true");
+a.removeAttribute("nomodule");
+is(a.noModule, false, "HTMLScriptElement without nomodule attribute has noModule set to false");
+a.noModule = true;
+ok(a.hasAttribute('nomodule'), "HTMLScriptElement.noModule = true add the nomodule attribute");
+
+var b = document.getElementById("b");
+is(b.noModule, false, "HTMLScriptElement without nomodule attribute has noModule set to false");
+b.noModule = true;
+ok(b.hasAttribute('nomodule'), "HTMLScriptElement.noModule = true add the nomodule attribute");
+  </script>
+
+  <script>var foo = 42;</script>
+  <script nomodule>foo = 43;</script>
+  <script>
+is(foo, 42, "nomodule HTMLScriptElements should not be executed in modern browsers");
+finish();
+  </script>
+</body>
+</html>

dom/html/test/file_script_nomodule.html

@@ -0,0 +1,32 @@
+<html>
+<body>
+  <script>
+// Helper methods.
+function ok(a, msg) {
+  parent.postMessage({ check: !!a, msg }, "*")
+}
+
+function is(a, b, msg) {
+  ok(a === b, msg);
+}
+
+function finish() {
+  parent.postMessage({ done: true }, "*");
+}
+  </script>
+
+  <script id="a" nomodule>42</script>
+  <script>
+// Let's test the behavior of nomodule attribute and noModule getter/setter.
+var a = document.getElementById("a");
+ok(!("noModule" in a), "When modules are disabled HTMLScriptElement.noModule is not defined");
+  </script>
+
+  <script>var foo = 42;</script>
+  <script nomodule>foo = 43;</script>
+  <script>
+is(foo, 43, "nomodule attribute is ignored when modules are disabled");
+finish();
+  </script>
+</body>
+</html>

dom/html/test/mochitest.ini

@@ -605,3 +605,7 @@ skip-if = os == "android" # up/down arrow keys not supported on android
 [test_bug1295719_event_sequence_for_number_keys.html]
 [test_bug1310865.html]
 [test_bug1315146.html]
++[test_script_module.html]
++support-files =
++  file_script_module.html
++  file_script_nomodule.html

dom/html/test/test_script_module.html

@@ -0,0 +1,56 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test for HTMLScriptElement with nomodule attribute</title>
+  <script type="text/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+
+<body>
+  <script>
+onmessage = (e) => {
+  if ("done" in e.data) {
+    next();
+  } else if ("check" in e.data) {
+    ok(e.data.check, e.data.msg);
+  } else {
+    ok(false, "Unknown message");
+  }
+}
+
+var tests = [
+  function() {
+    SpecialPowers.pushPrefEnv({"set":[["dom.moduleScripts.enabled", true]]})
+    .then(() => {
+      var ifr = document.createElement('iframe');
+      ifr.src = "file_script_module.html";
+      document.body.appendChild(ifr);
+    });
+  },
+
+  function() {
+    SpecialPowers.pushPrefEnv({"set":[["dom.moduleScripts.enabled", false]]})
+    .then(() => {
+      var ifr = document.createElement('iframe');
+      ifr.src = "file_script_nomodule.html";
+      document.body.appendChild(ifr);
+    });
+  },
+];
+
+SimpleTest.waitForExplicitFinish();
+next();
+
+function next() {
+  if (!tests.length) {
+    SimpleTest.finish();
+    return;
+  }
+
+  var test = tests.shift();
+  test();
+}
+  </script>
+
+</body>
+</html>