Switch to mojo localstorage backend by default.

third_party/WebKit/LayoutTests/VirtualTestSuites

 [
   {
     "prefix": "color_space",
     "base": "fast/canvas/color-space",
     "args": ["--enable-color-correct-rendering",
              "--enable-blink-features=ColorCanvasExtensions"]
   },
   {
     "prefix": "gpu",
     "base": "fast/canvas",
@@ skipping 431 matching lines @@
     "args": ["--enable-blink-features=FeaturePolicy"]
   },
   {
     "prefix": "feature-policy-experimental-features",
     "base": "http/tests/feature-policy-experimental-features",
     "args": ["--enable-blink-features=FeaturePolicy,FeaturePolicyExperimentalFeatures"]
   },
   {
     "prefix": "mojo-localstorage",
     "base": "external/wpt/webstorage",
-    "args": ["--mojo-local-storage"]
+    "args": ["--disable-mojo-local-storage"]
   },
   {
     "prefix": "mojo-localstorage",
     "base": "storage/domstorage/localstorage",
-    "args": ["--mojo-local-storage"]
+    "args": ["--disable-mojo-local-storage"]
   },
   {
     "prefix": "print_browser",
     "base": "print_testharness",
     "args": ["--enable-print-browser"]
   },
   {
     "prefix": "experimental-canvas-features",
     "base": "fast/canvas-experimental",
     "args": ["--enable-experimental-canvas-features"]
   },
   {
     "prefix": "new-remote-playback-pipeline",
     "base": "media/remoteplayback",
     "args": ["--enable-features=NewRemotePlaybackPipeline"]
   },
   {
     "prefix": "new-remote-playback-pipeline",
     "base": "media/controls",
     "args": ["--enable-features=NewRemotePlaybackPipeline"]
   }
 ]