Make PointerEvent an experimental web platform feature.

third_party/WebKit/LayoutTests/VirtualTestSuites

 [
   {
     "prefix": "gpu",
     "base": "fast/canvas",
     "args": ["--enable-accelerated-2d-canvas",
              "--disable-display-list-2d-canvas"]
   },
   {
     "prefix": "display_list_2d_canvas",
     "base": "fast/canvas",
@@ skipping 140 matching lines @@
     "prefix": "scroll_customization",
     "base": "fast/events/touch",
     "args": ["--enable-blink-features=ScrollCustomization"]
   },
   {
     "prefix": "smoothscrolling",
     "base": "fast/events/touch/gesture",
     "args": ["--enable-smooth-scrolling"]
   },
   {
-    "prefix": "pointerevent",
-    "base": "fast/events",
-    "args": ["--enable-blink-features=PointerEvent"]
-  },
-  {
-    "prefix": "pointerevent",
-    "base": "imported/wpt/pointerevents",
-    "args": ["--enable-blink-features=PointerEvent"]
-  },
-  {
-    "prefix": "pointerevent",
-    "base": "inspector/sources/debugger-breakpoints",
-    "args": ["--enable-blink-features=PointerEvent"]
-  },
-  {
     "prefix": "mediasession",
     "base": "media/mediasession",
     "args": ["--enable-blink-features=MediaSession"]
   },
   {
     "prefix": "sharedarraybuffer",
     "base": "fast/workers",
     "args": ["--js-flags=--harmony-sharedarraybuffer",
              "--enable-blink-features=SharedArrayBuffer"]
   },
@@ skipping 71 matching lines @@
     "prefix": "documentwriteevaluator",
     "base": "http/tests/preload/document-write",
     "args": ["--enable-blink-features=DocumentWriteEvaluator"]
   },
   {
     "prefix": "asyncawait",
     "base": "inspector/sources/debugger-async/async-await",
     "args": ["--js-flags=--harmony-async-await"]
   }
 ]