Disallow certain blocking DOM calls during microtask execution.

third_party/WebKit/Source/bindings/templates/methods.cpp

 {% from 'utilities.cpp' import declare_enum_validation_variable, v8_value_to_local_cpp_value, check_origin_trial %}
 
 {##############################################################################}
 {% macro generate_method(method, world_suffix) %}
 {% if method.returns_promise and method.has_exception_state %}
 static void {{method.name}}{{method.overload_index}}Method{{world_suffix}}Promise(const v8::FunctionCallbackInfo<v8::Value>& info, ExceptionState& exceptionState)
 {% else %}
 static void {{method.name}}{{method.overload_index}}Method{{world_suffix}}(const v8::FunctionCallbackInfo<v8::Value>& info)
 {% endif %}
 {
@@ skipping 392 matching lines @@
         {% if method.visible %}
         {% filter runtime_enabled(not overloads.runtime_enabled_function_all and
                                   method.runtime_enabled_function) %}
         if ({{test}}) {
             {% if method.measure_as and not overloads.measure_all_as %}
             UseCounter::countIfNotPrivateScript(info.GetIsolate(), currentExecutionContext(info.GetIsolate()), UseCounter::{{method.measure_as('Method')}});
             {% endif %}
             {% if method.deprecate_as and not overloads.deprecate_all_as %}
             Deprecation::countDeprecationIfNotPrivateScript(info.GetIsolate(), currentExecutionContext(info.GetIsolate()), UseCounter::{{method.deprecate_as}});
             {% endif %}
+            {% if method.not_during_microtasks %}
+            if (v8::MicrotasksScope::IsRunningMicrotasks(info.GetIsolate()))
+                return;

[haraken, 2016/05/03 12:10:50]

As Elliott is suggesting in the bug, would it be better to add a console message
here?

+            {% endif %}
             {{method.name}}{{method.overload_index}}Method{{world_suffix}}(info);
             return;
         }
         {% endfilter %}
         {% endif %}
         {% endfor %}
         break;
     {% endfor %}
     {% if is_partial or not overloads.has_partial_overloads %}
     default:
@@ skipping 66 matching lines @@
     {% if not method.overloads %}{# Overloaded methods are measured in overload_resolution_method() #}
     {% if method.measure_as %}
     UseCounter::countIfNotPrivateScript(info.GetIsolate(), currentExecutionContext(info.GetIsolate()), UseCounter::{{method.measure_as('Method')}});
     {% endif %}
     {% if method.deprecate_as %}
     Deprecation::countDeprecationIfNotPrivateScript(info.GetIsolate(), currentExecutionContext(info.GetIsolate()), UseCounter::{{method.deprecate_as}});
     {% endif %}
     {% if method.origin_trial_enabled_function %}
     {{check_origin_trial(method) | indent}}
     {% endif %}
+    {% if method.not_during_microtasks %}
+    if (v8::MicrotasksScope::IsRunningMicrotasks(info.GetIsolate()))
+        return;
+    {% endif %}
     {% endif %}{# not method.overloads #}
     {% if world_suffix in method.activity_logging_world_list %}
     ScriptState* scriptState = ScriptState::from(info.GetIsolate()->GetCurrentContext());
     V8PerContextData* contextData = scriptState->perContextData();
     {% if method.activity_logging_world_check %}
     if (scriptState->world().isIsolatedWorld() && contextData && contextData->activityLogger())
     {% else %}
     if (contextData && contextData->activityLogger()) {
     {% endif %}
         ExceptionState exceptionState(ExceptionState::ExecutionContext, "{{method.name}}", "{{interface_name}}", info.Holder(), info.GetIsolate());
@@ skipping 179 matching lines @@
 {% filter runtime_enabled(method.overloads.runtime_enabled_function_all
                           if method.overloads else
                           method.runtime_enabled_function) %}
 const V8DOMConfiguration::MethodConfiguration {{method.name}}MethodConfiguration = {{method_configuration(method)}};
 V8DOMConfiguration::installMethod(isolate, world, v8::Local<v8::Object>(), prototypeObject, interfaceObject, signature, {{method.name}}MethodConfiguration);
 {% endfilter %}{# runtime_enabled() #}
 {% endfilter %}{# exposed() #}
 {% endfor %}
 {% endif %}
 {%- endmacro %}