[DevTools] Better label for async function call stacks

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 237 matching lines @@
     "prefix": "scalefactor200withzoom",
     "base": "fast/hidpi/static",
     "args": ["--force-device-scale-factor=2", "--enable-use-zoom-for-dsf"]
   },
   {
     "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"]
-  },
-  {
     "prefix": "wheelscrolllatching",
     "base": "fast/events/wheel",
     "args": ["--enable-features=TouchpadAndWheelScrollLatching"]
   },
   {
     "prefix": "parsehtmlonmainthread_sync",
     "base": "fast/parser",
     "args": ["--blink-settings=parseHTMLOnMainThreadSyncTokenize=true"]
   },
   {
@@ skipping 30 matching lines @@
     "prefix": "layout_ng",
     "base": "fast/block/basic",
     "args": ["--enable-blink-features=LayoutNG"]
   },
   {
     "prefix": "layout_ng",
     "base": "fast/block/margin-collapse",
     "args": ["--enable-blink-features=LayoutNG"]
   }
 ]