Sync the DOMParser interface with spec

Source/core/xml/DOMParser.idl

Index: Source/core/xml/DOMParser.idl
diff --git a/Source/core/xml/DOMParser.idl b/Source/core/xml/DOMParser.idl
index aa390c5cbae0c0b0e631e0edbafbb579a96ecdee..ba2a0b4faba2aa7f34ecaa2f2882f1d9e00fbfd1 100644
--- a/Source/core/xml/DOMParser.idl
+++ b/Source/core/xml/DOMParser.idl
@@ -17,10 +17,20 @@
  * Boston, MA 02110-1301, USA.
  */
 
+// https://dvcs.w3.org/hg/innerhtml/raw-file/tip/index.html#the-domparser-interface
+
+enum SupportedType {
+    "text/html",
+    "text/xml",
+    "application/xml",
+    "application/xhtml+xml",
+    "image/svg+xml"
+};
+
 [
+    Constructor,
+    TypeChecking=Interface,

[Jens Widell, 2015/01/16 15:10:45]

[TypeChecking=Interface] will have no effect since there are no interface type
arguments to any method in the interface.

Conversion to string can't fail, and enums are always checked.

[philipj_slow, 2015/01/16 19:20:07]

Ah, I was assuming things without testing. I'll revert this bit.

     WillBeGarbageCollected,
-    Constructor
 ] interface DOMParser {
-    [RaisesException] Document parseFromString([Default=Undefined] optional DOMString str,
-                             [Default=Undefined] optional DOMString contentType);
+    Document parseFromString(DOMString str, SupportedType type);
 };