Add a public API to enable/disable blink runtime features by name

Source/core/scripts/templates/RuntimeEnabledFeatures.cpp.tmpl

Index: Source/core/scripts/templates/RuntimeEnabledFeatures.cpp.tmpl
diff --git a/Source/core/scripts/templates/RuntimeEnabledFeatures.cpp.tmpl b/Source/core/scripts/templates/RuntimeEnabledFeatures.cpp.tmpl
index 4affac1f8eb467cbbb91859d8136b0dcf47ce75b..6f29301cf0269560eb707a3b27c98b43366b1c5e 100644
--- a/Source/core/scripts/templates/RuntimeEnabledFeatures.cpp.tmpl
+++ b/Source/core/scripts/templates/RuntimeEnabledFeatures.cpp.tmpl
@@ -21,5 +21,18 @@ bool RuntimeEnabledFeatures::is{{feature.name}}Enabled = false;
 {%- endcall %}
 {%- endfor %}
 
+bool RuntimeEnabledFeatures::setFeatureEnabled(const String& feature, bool enable)
+{
+{%- for feature in features if feature.command_line_flag and not feature.custom %}
+{%- call wrap_with_condition(feature.condition) %}
+    if (feature == "{{feature.name}}") {
+      set{{feature.name}}Enabled(enable);
+      return true;
+    }
+{%- endcall %}
+{%- endfor %}
+    return false;
+}
+
 } // namespace WebCore