Move PlatformEventDispatcher implementations to the Oilpan heap.

Source/modules/device_orientation/DeviceMotionDispatcher.cpp

Index: Source/modules/device_orientation/DeviceMotionDispatcher.cpp
diff --git a/Source/modules/device_orientation/DeviceMotionDispatcher.cpp b/Source/modules/device_orientation/DeviceMotionDispatcher.cpp
index b5c51b0a4ae9483f01b18e3e987a65893c535111..92a469b16f098a2e10cba55ae94bb6e905d8742b 100644
--- a/Source/modules/device_orientation/DeviceMotionDispatcher.cpp
+++ b/Source/modules/device_orientation/DeviceMotionDispatcher.cpp
@@ -39,8 +39,8 @@ namespace blink {
 
 DeviceMotionDispatcher& DeviceMotionDispatcher::instance()
 {
-    DEFINE_STATIC_LOCAL(DeviceMotionDispatcher, deviceMotionDispatcher, ());
-    return deviceMotionDispatcher;
+    DEFINE_STATIC_LOCAL(Persistent<DeviceMotionDispatcher>, deviceMotionDispatcher, (new DeviceMotionDispatcher()));
+    return *deviceMotionDispatcher;
 }
 
 DeviceMotionDispatcher::DeviceMotionDispatcher()
@@ -51,6 +51,12 @@ DeviceMotionDispatcher::~DeviceMotionDispatcher()
 {
 }
 
+void DeviceMotionDispatcher::trace(Visitor* visitor)
+{
+    visitor->trace(m_lastDeviceMotionData);
+    PlatformEventDispatcher::trace(visitor);
+}
+
 void DeviceMotionDispatcher::startListening()
 {
     Platform::current()->startListening(WebPlatformEventDeviceMotion, this);