Bug 1834096 - Rewrite JS language check to use MIME type check r=peterv

Rewrote the JS language check util function to use the existing more
robust JS MIME type checker instead of implementing its own checks
(passing "text/{given}").

16 WPT subtests now newly pass.

WPT tests: https://wpt.fyi/results/html/semantics/scripting-1/the-script-element/script-type-and-language-js.html

Differential Revision: https://phabricator.services.mozilla.com/D178567

dom/base/nsContentUtils.cpp

@@ -1559,15 +1559,11 @@ bool nsContentUtils::GetPseudoAttributeValue(const nsString& aSource,
 }
 
 bool nsContentUtils::IsJavaScriptLanguage(const nsString& aName) {
-  return aName.LowerCaseEqualsLiteral("javascript") ||
-         aName.LowerCaseEqualsLiteral("livescript") ||
-         aName.LowerCaseEqualsLiteral("mocha") ||
-         aName.LowerCaseEqualsLiteral("javascript1.0") ||
-         aName.LowerCaseEqualsLiteral("javascript1.1") ||
-         aName.LowerCaseEqualsLiteral("javascript1.2") ||
-         aName.LowerCaseEqualsLiteral("javascript1.3") ||
-         aName.LowerCaseEqualsLiteral("javascript1.4") ||
-         aName.LowerCaseEqualsLiteral("javascript1.5");
+  // Create MIME type as "text/" + given input
+  nsAutoString mimeType(u"text/");
+  mimeType.Append(aName);
+
+  return IsJavascriptMIMEType(mimeType);
 }
 
 void nsContentUtils::SplitMimeType(const nsAString& aValue, nsString& aType,

testing/web-platform/meta/html/semantics/scripting-1/the-script-element/script-type-and-language-js-xhtml.xhtml.ini

@@ -3,27 +3,3 @@
     if (os == "android") and fission: [OK, TIMEOUT]
   [Script shouldn't run with type=" "]
     expected: FAIL
-
-  [Script should run with language="ecmascript"]
-    expected: FAIL
-
-  [Script should run with language="jscript"]
-    expected: FAIL
-
-  [Script should run with language="x-ecmascript"]
-    expected: FAIL
-
-  [Script should run with language="x-javascript"]
-    expected: FAIL
-
-  [Script should run with language="ECMASCRIPT"]
-    expected: FAIL
-
-  [Script should run with language="JSCRIPT"]
-    expected: FAIL
-
-  [Script should run with language="X-ECMASCRIPT"]
-    expected: FAIL
-
-  [Script should run with language="X-JAVASCRIPT"]
-    expected: FAIL

testing/web-platform/meta/html/semantics/scripting-1/the-script-element/script-type-and-language-js.html.ini

@@ -3,27 +3,3 @@
     if (os == "android") and fission: [OK, TIMEOUT]
   [Script shouldn't run with type=" "]
     expected: FAIL
-
-  [Script should run with language="ecmascript"]
-    expected: FAIL
-
-  [Script should run with language="jscript"]
-    expected: FAIL
-
-  [Script should run with language="x-ecmascript"]
-    expected: FAIL
-
-  [Script should run with language="x-javascript"]
-    expected: FAIL
-
-  [Script should run with language="ECMASCRIPT"]
-    expected: FAIL
-
-  [Script should run with language="JSCRIPT"]
-    expected: FAIL
-
-  [Script should run with language="X-ECMASCRIPT"]
-    expected: FAIL
-
-  [Script should run with language="X-JAVASCRIPT"]
-    expected: FAIL