Fixing up element_types_test to work properly in checked mode.

tools/dom/dom.json

 {
   "AbstractWorker": {
     "comment": "http://www.w3.org/TR/workers/#the-abstractworker-abstract-interface",
     "members": {
       "addEventListener": {},
       "dispatchEvent": {},
       "onerror": {},
       "removeEventListener": {}
     },
     "support_level": "stable"
@@ skipping 4357 matching lines @@
         "comment": "http://www.whatwg.org/specs/web-apps/current-work/multipage/obsolete.html#HTMLMenuElement-partial",
         "dart_action": "suppress",
         "support_level": "deprecated"
       }
     },
     "support_level": "stable"
   },
   "HTMLMetaElement": {
     "comment": "http://www.whatwg.org/specs/web-apps/current-work/multipage/semantics.html#the-meta-element",
     "members": {
+      "HTMLMetaElement": {},
       "content": {},
       "httpEquiv": {},
       "name": {},
       "scheme": {
         "comment": "http://www.whatwg.org/specs/web-apps/current-work/multipage/obsolete.html#HTMLMetaElement-partial",
         "dart_action": "suppress",
         "support_level": "deprecated"
       }
     },
     "support_level": "stable"
@@ skipping 237 matching lines @@
       },
       "max": {},
       "position": {},
       "value": {}
     },
     "support_level": "stable"
   },
   "HTMLQuoteElement": {
     "comment": "http://www.whatwg.org/specs/web-apps/current-work/multipage/grouping-content.html#the-blockquote-element",
     "members": {
+      "HTMLQuoteElement": {},
       "cite": {}
     },
     "support_level": "stable"
   },
   "HTMLScriptElement": {
     "comment": "http://www.whatwg.org/specs/web-apps/current-work/multipage/scripting-1.html#the-script-element",
     "members": {
       "HTMLScriptElement": {},
       "async": {},
       "charset": {},
@@ skipping 52 matching lines @@
       "validationMessage": {},
       "validity": {},
       "value": {},
       "willValidate": {}
     },
     "support_level": "stable"
   },
   "HTMLShadowElement": {
     "comment": "https://dvcs.w3.org/hg/webcomponents/raw-file/tip/spec/shadow/index.html#shadow-element",
     "members": {
+      "HTMLShadowElement": {},
       "olderShadowRoot": {},
       "resetStyleInheritance": {}
     },
     "support_level": "experimental"
   },
   "HTMLSourceElement": {
     "comment": "http://www.whatwg.org/specs/web-apps/current-work/multipage/the-video-element.html#the-source-element",
     "members": {
       "HTMLSourceElement": {},
       "media": {},
@@ skipping 7393 matching lines @@
       "importStylesheet": {},
       "removeParameter": {},
       "reset": {},
       "setParameter": {},
       "transformToDocument": {},
       "transformToFragment": {}
     },
     "support_level": "nonstandard"
   }
 }