Allow setting runtime-enabled features from a string.

public/web/WebRuntimeFeatures.h

Index: public/web/WebRuntimeFeatures.h
diff --git a/public/web/WebRuntimeFeatures.h b/public/web/WebRuntimeFeatures.h
index 79c4125b54a6b1384ee9bb0dbf1cd0ea131101b0..5a2e88ab300812baec31613661c806ad087b05ae 100644
--- a/public/web/WebRuntimeFeatures.h
+++ b/public/web/WebRuntimeFeatures.h
@@ -32,6 +32,7 @@
 #define WebRuntimeFeatures_h
 
 #include "../platform/WebCommon.h"
+#include "../platform/WebString.h"
 
 namespace blink {
 
@@ -42,6 +43,10 @@ public:
     BLINK_EXPORT static void enableExperimentalFeatures(bool);
     BLINK_EXPORT static void enableTestOnlyFeatures(bool);
 
+    // Enables a feature by its string identifier from
+    // RuntimeEnabledFeatures.in.
+    BLINK_EXPORT static void enableFeatureFromString(const WebString& name, bool enable);
+
     BLINK_EXPORT static void enableApplicationCache(bool);
 
     BLINK_EXPORT static void enableDatabase(bool);