Allow Web Animations CSS flag to be turned off as well as on

content/child/runtime_features.cc

Index: content/child/runtime_features.cc
diff --git a/content/child/runtime_features.cc b/content/child/runtime_features.cc
index 28eb9f3b83b45d18f56f5658dc4436a301a0edb1..83ab6b300cdc6d4956fd2ec29f56e7e9abd28e36 100644
--- a/content/child/runtime_features.cc
+++ b/content/child/runtime_features.cc
@@ -110,11 +110,15 @@ void SetRuntimeFeaturesDefaultsAndUpdateFromArgs(
   if (command_line.HasSwitch(switches::kDisablePrefixedEncryptedMedia))
     WebRuntimeFeatures::enablePrefixedEncryptedMedia(false);
 
+  // FIXME: Remove the enable switch once Web Animations CSS is enabled by
+  // default in Blink.
   if (command_line.HasSwitch(switches::kEnableWebAnimationsCSS))
-    WebRuntimeFeatures::enableWebAnimationsCSS();
+    WebRuntimeFeatures::enableWebAnimationsCSS(true);
+  else if (command_line.HasSwitch(switches::kDisableWebAnimationsCSS))
+    WebRuntimeFeatures::enableWebAnimationsCSS(false);
 
   if (command_line.HasSwitch(switches::kEnableWebAnimationsSVG))
-    WebRuntimeFeatures::enableWebAnimationsSVG();
+    WebRuntimeFeatures::enableWebAnimationsSVG(true);
 
   if (command_line.HasSwitch(switches::kEnableWebMIDI))
     WebRuntimeFeatures::enableWebMIDI(true);