Make Time functions go through the Platform layer.

src/default-platform.h

Index: src/default-platform.h
diff --git a/src/default-platform.h b/src/default-platform.h
index fe1bf8e2d64e57349309fdab70c973af2fb99eb9..ee89b6fa60dcdf5b267054b0e6e5fcfb432b391d 100644
--- a/src/default-platform.h
+++ b/src/default-platform.h
@@ -43,6 +43,11 @@ class DefaultPlatform : public Platform {
       Task *task, ExpectedRuntime expected_runtime) V8_OVERRIDE;
   virtual void CallOnForegroundThread(v8::Isolate *isolate,
                                       Task *task) V8_OVERRIDE;
+  virtual int64_t CurrentTime() V8_OVERRIDE;
+  virtual int64_t CurrentTimeFromSystemTime() V8_OVERRIDE;
+  virtual int64_t TimeTicksNow() V8_OVERRIDE;
+  virtual int64_t TimeTicksHighResNow() V8_OVERRIDE;
+  virtual bool TimeTicksHasHighRes() V8_OVERRIDE;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(DefaultPlatform);