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..ef9fbbaf4d6634c5b2619b7f937ebcc5bd8a9f74 100644
--- a/Source/core/xml/DOMParser.idl
+++ b/Source/core/xml/DOMParser.idl
@@ -17,10 +17,19 @@
  * 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"
+};
+
 [
     WillBeGarbageCollected,
     Constructor
 ] interface DOMParser {
-    [RaisesException] Document parseFromString([Default=Undefined] optional DOMString str,
-                             [Default=Undefined] optional DOMString contentType);
+    Document parseFromString(DOMString str, SupportedType type);
 };