Add support for idle tasks to the default platform

include/libplatform/libplatform.h

Index: include/libplatform/libplatform.h
diff --git a/include/libplatform/libplatform.h b/include/libplatform/libplatform.h
index 40f3f668927f4e6e9afdf2e8ab989676040c8e72..cab467fd50704f6ddc35dcae46e8f0a68e8b515e 100644
--- a/include/libplatform/libplatform.h
+++ b/include/libplatform/libplatform.h
@@ -35,6 +35,17 @@ V8_PLATFORM_EXPORT bool PumpMessageLoop(v8::Platform* platform,
                                         v8::Isolate* isolate);
 
 /**
+ * Runs pending idle tasks for at most |idle_time_in_seconds| seconds.
+ *
+ * The caller has to make sure that this is called from the right thread.
+ * This call does not block if no task is pending. The |platform| has to be
+ * created using |CreateDefaultPlatform|.
+ */
+V8_PLATFORM_EXPORT void RunIdleTasks(v8::Platform* platform,
+                                     v8::Isolate* isolate,
+                                     double idle_time_in_seconds);
+
+/**
  * Attempts to set the tracing controller for the given platform.
  *
  * The |platform| has to be created using |CreateDefaultPlatform|.