Fix dart2js type warnings

tools/dom/dom.json

 {
   "ANGLEInstancedArrays": {
     "members": {
       "VERTEX_ATTRIB_ARRAY_DIVISOR_ANGLE": {
         "support_level": "untriaged"
       },
       "drawArraysInstancedANGLE": {
         "support_level": "untriaged"
       },
       "drawElementsInstancedANGLE": {
@@ skipping 1628 matching lines @@
     "comment": "http://www.w3.org/TR/file-system-api/#idl-def-DirectoryReaderSync",
     "members": {
       "readEntries": {}
     },
     "support_level": "experimental"
   },
   "Document": {
     "comment": "http://dom.spec.whatwg.org/#interface-document",
     "members": {
       "URL": {},
+      "addEventListener": {
+        "support_level": "untriaged"
+      },
       "adoptNode": {},
       "anchors": {
         "dart_action": "suppress"
       },
       "applets": {
         "dart_action": "suppress",
         "support_level": "deprecated"
       },
       "body": {},
       "caretRangeFromPoint": {
@@ skipping 66 matching lines @@
       },
       "createTreeWalker": {},
       "currentScript": {
         "support_level": "untriaged"
       },
       "defaultCharset": {
         "dart_action": "suppress",
         "support_level": "nonstandard"
       },
       "defaultView": {},
+      "dispatchEvent": {
+        "support_level": "untriaged"
+      },
       "doctype": {
         "dart_action": "suppress"
       },
       "documentElement": {},
       "documentURI": {},
       "domain": {},
       "elementFromPoint": {},
       "evaluate": {
         "dart_action": "suppress"
       },
@@ skipping 211 matching lines @@
       },
       "queryCommandEnabled": {},
       "queryCommandIndeterm": {},
       "queryCommandState": {},
       "queryCommandSupported": {},
       "queryCommandValue": {},
       "querySelector": {},
       "querySelectorAll": {},
       "readyState": {},
       "referrer": {},
+      "removeEventListener": {
+        "support_level": "untriaged"
+      },
       "securityPolicy": {
         "comment": "https://dvcs.w3.org/hg/content-security-policy/raw-file/tip/csp-specification.dev.html#idl-def-SecurityPolicy",
         "support_level": "experimental"
       },
       "selectedStylesheetSet": {
         "comment": "http://dev.w3.org/csswg/cssom/#widl-Document-selectedStyleSheetSet"
       },
       "styleSheets": {},
       "title": {},
       "webkitCancelFullScreen": {
@@ skipping 144 matching lines @@
     "support_level": "experimental"
   },
   "Element": {
     "comment": "http://dom.spec.whatwg.org/#interface-element",
     "members": {
       "ALLOW_KEYBOARD_INPUT": {
         "comment": "https://dvcs.w3.org/hg/fullscreen/raw-file/tip/Overview.html#dom-element-requestfullscreen",
         "dart_action": "suppress",
         "support_level": "deprecated"
       },
+      "addEventListener": {
+        "support_level": "untriaged"
+      },
       "attributes": {},
       "blur": {},
       "childElementCount": {},
       "children": {
         "comment": "http://www.whatwg.org/specs/web-apps/2007-10-26/multipage/section-elements.html#htmlelement",
         "dart_action": "stable",
         "support_level": "nonstandard"
       },
       "classList": {
         "comment": "http://www.whatwg.org/specs/web-apps/current-work/multipage/elements.html#dom-classlist"
@@ skipping 18 matching lines @@
         "support_level": "experimental"
       },
       "dataset": {
         "comment": "http://www.whatwg.org/specs/web-apps/current-work/multipage/elements.html#dom-dataset"
       },
       "dir": {
         "comment": "http://www.whatwg.org/specs/web-apps/2007-10-26/multipage/section-elements.html#htmlelement",
         "dart_action": "stable",
         "support_level": "nonstandard"
       },
+      "dispatchEvent": {
+        "support_level": "untriaged"
+      },
       "draggable": {
         "comment": "http://www.whatwg.org/specs/web-apps/2007-10-26/multipage/section-elements.html#htmlelement",
         "dart_action": "stable",
         "support_level": "nonstandard"
       },
       "firstElementChild": {},
       "focus": {},
       "getAttribute": {
         "support_level": "untriaged"
       },
@@ skipping 250 matching lines @@
         "dart_action": "stable",
         "support_level": "nonstandard"
       },
       "removeAttribute": {},
       "removeAttributeNS": {},
       "removeAttributeNode": {
         "comment": "http://dom.spec.whatwg.org/#dom-element-removeattributenode",
         "dart_action": "suppress",
         "support_level": "deprecated"
       },
+      "removeEventListener": {
+        "support_level": "untriaged"
+      },
       "scrollByLines": {},
       "scrollByPages": {},
       "scrollHeight": {},
       "scrollIntoView": {
         "comment": "http://dev.w3.org/csswg/cssom-view/#widl-Element-scrollIntoView-void-boolean-top"
       },
       "scrollIntoViewIfNeeded": {
         "comment": "http://docs.webplatform.org/wiki/dom/methods/scrollIntoViewIfNeeded",
         "support_level": "nonstandard"
       },
@@ skipping 699 matching lines @@
     "comment": "http://dev.w3.org/geo/api/spec-source.html#position",
     "dart_action": "unstable",
     "members": {
       "coords": {},
       "timestamp": {}
     },
     "support_level": "stable"
   },
   "GlobalEventHandlers": {
     "members": {
+      "addEventListener": {
+        "support_level": "untriaged"
+      },
+      "dispatchEvent": {
+        "support_level": "untriaged"
+      },
       "onabort": {
         "support_level": "untriaged"
       },
       "onblur": {
         "support_level": "untriaged"
       },
       "oncanplay": {
         "support_level": "untriaged"
       },
       "oncanplaythrough": {
@@ skipping 135 matching lines @@
         "support_level": "untriaged"
       },
       "ontimeupdate": {
         "support_level": "untriaged"
       },
       "onvolumechange": {
         "support_level": "untriaged"
       },
       "onwaiting": {
         "support_level": "untriaged"
+      },
+      "removeEventListener": {
+        "support_level": "untriaged"
       }
     },
     "support_level": "untriaged"
   },
   "HTMLAllCollection": {
     "comment": "http://www.whatwg.org/specs/web-apps/current-work/multipage/obsolete.html#dom-document-all",
     "dart_action": "suppress",
     "members": {
       "__getter__": {},
       "item": {},
@@ skipping 167 matching lines @@
   },
   "HTMLBodyElement": {
     "comment": "http://www.whatwg.org/specs/web-apps/current-work/multipage/sections.html#the-body-element",
     "members": {
       "HTMLBodyElement": {},
       "aLink": {
         "comment": "http://www.whatwg.org/specs/web-apps/current-work/multipage/obsolete.html#HTMLBodyElement-partial",
         "dart_action": "suppress",
         "support_level": "deprecated"
       },
+      "addEventListener": {
+        "support_level": "untriaged"
+      },
       "background": {
         "comment": "http://www.whatwg.org/specs/web-apps/current-work/multipage/obsolete.html#HTMLBodyElement-partial",
         "dart_action": "suppress",
         "support_level": "deprecated"
       },
       "bgColor": {
         "comment": "http://www.whatwg.org/specs/web-apps/current-work/multipage/obsolete.html#HTMLBodyElement-partial",
         "dart_action": "suppress",
         "support_level": "deprecated"
       },
+      "dispatchEvent": {
+        "support_level": "untriaged"
+      },
       "link": {
         "comment": "http://www.whatwg.org/specs/web-apps/current-work/multipage/obsolete.html#HTMLBodyElement-partial",
         "dart_action": "suppress",
         "support_level": "deprecated"
       },
       "onbeforeunload": {},
       "onblur": {},
       "onerror": {},
       "onfocus": {},
       "onhashchange": {},
       "onload": {},
       "onmessage": {},
       "onoffline": {},
       "ononline": {},
       "onpopstate": {},
       "onresize": {},
       "onscroll": {
         "support_level": "untriaged"
       },
       "onstorage": {},
       "onunload": {},
+      "removeEventListener": {
+        "support_level": "untriaged"
+      },
       "text": {
         "comment": "http://www.whatwg.org/specs/web-apps/current-work/multipage/obsolete.html#HTMLBodyElement-partial",
         "dart_action": "suppress",
         "support_level": "deprecated"
       },
       "vLink": {
         "comment": "http://www.whatwg.org/specs/web-apps/current-work/multipage/obsolete.html#HTMLBodyElement-partial",
         "dart_action": "suppress",
         "support_level": "deprecated"
       }
@@ skipping 200 matching lines @@
       },
       "write": {},
       "writeln": {}
     },
     "support_level": "stable"
   },
   "HTMLElement": {
     "comment": "http://www.whatwg.org/specs/web-apps/2007-10-26/multipage/section-elements.html#htmlelement",
     "members": {
       "accessKey": {},
+      "addEventListener": {
+        "support_level": "untriaged"
+      },
       "children": {},
       "click": {},
       "contentEditable": {},
       "dir": {},
+      "dispatchEvent": {
+        "support_level": "untriaged"
+      },
       "draggable": {},
       "getInputContext": {
         "comment": "http://www.w3.org/TR/ime-api/#the-getinputcontext-method",
         "support_level": "experimental"
       },
       "hidden": {},
       "id": {},
       "innerHTML": {},
       "innerText": {
         "dart_action": "suppress",
@@ skipping 167 matching lines @@
         "support_level": "untriaged"
       },
       "onwaiting": {
         "support_level": "untriaged"
       },
       "outerHTML": {},
       "outerText": {
         "dart_action": "suppress",
         "support_level": "nonstandard"
       },
+      "removeEventListener": {
+        "support_level": "untriaged"
+      },
       "spellcheck": {
         "comment": "http://blog.whatwg.org/the-road-to-html-5-spellchecking",
         "dart_action": "experimental",
         "support_level": "nonstandard"
       },
       "tabIndex": {},
       "title": {},
       "translate": {},
       "webkitdropzone": {
         "comment": "http://www.whatwg.org/specs/web-apps/current-work/multipage/dnd.html#the-dropzone-attribute",
@@ skipping 4308 matching lines @@
     "members": {
       "createEvent": {},
       "rootElement": {}
     },
     "support_level": "stable"
   },
   "SVGElement": {
     "comment": "http://www.w3.org/TR/SVG/types.html#InterfaceSVGElement",
     "dart_action": "unstable",
     "members": {
+      "addEventListener": {
+        "support_level": "untriaged"
+      },
       "className": {
         "support_level": "untriaged"
       },
+      "dispatchEvent": {
+        "support_level": "untriaged"
+      },
       "getPresentationAttribute": {
         "support_level": "untriaged"
       },
       "id": {},
       "onabort": {
         "support_level": "untriaged"
       },
       "onblur": {
         "support_level": "untriaged"
       },
@@ skipping 141 matching lines @@
       "ontimeupdate": {
         "support_level": "untriaged"
       },
       "onvolumechange": {
         "support_level": "untriaged"
       },
       "onwaiting": {
         "support_level": "untriaged"
       },
       "ownerSVGElement": {},
+      "removeEventListener": {
+        "support_level": "untriaged"
+      },
       "style": {
         "support_level": "untriaged"
       },
       "viewportElement": {},
       "xmlbase": {},
       "xmllang": {
         "support_level": "untriaged"
       },
       "xmlspace": {
         "support_level": "untriaged"
@@ skipping 4979 matching lines @@
         "support_level": "untriaged"
       },
       "btoa": {
         "support_level": "untriaged"
       }
     },
     "support_level": "untriaged"
   },
   "WindowEventHandlers": {
     "members": {
+      "addEventListener": {
+        "support_level": "untriaged"
+      },
+      "dispatchEvent": {
+        "support_level": "untriaged"
+      },
       "onbeforeunload": {
         "support_level": "untriaged"
       },
       "onhashchange": {
         "support_level": "untriaged"
       },
       "onmessage": {
         "support_level": "untriaged"
       },
       "onoffline": {
         "support_level": "untriaged"
       },
       "ononline": {
         "support_level": "untriaged"
       },
       "onpopstate": {
         "support_level": "untriaged"
       },
       "onresize": {
         "support_level": "untriaged"
       },
       "onstorage": {
         "support_level": "untriaged"
       },
       "onunload": {
         "support_level": "untriaged"
+      },
+      "removeEventListener": {
+        "support_level": "untriaged"
       }
     },
     "support_level": "untriaged"
   },
   "WindowTimers": {
     "members": {
       "clearInterval": {
         "support_level": "untriaged"
       },
       "clearTimeout": {
@@ skipping 496 matching lines @@
       "importStylesheet": {},
       "removeParameter": {},
       "reset": {},
       "setParameter": {},
       "transformToDocument": {},
       "transformToFragment": {}
     },
     "support_level": "nonstandard"
   }
 }