Expose performance.memory in workers

Source/modules/performance/WorkerPerformance.cpp

Index: Source/modules/performance/WorkerPerformance.cpp
diff --git a/Source/modules/performance/WorkerPerformance.cpp b/Source/modules/performance/WorkerPerformance.cpp
index fe20882c6aa3540c37ea9e45c804140f5711bbac..394fae19e9dcda14275974088d910e68a2fd6e34 100644
--- a/Source/modules/performance/WorkerPerformance.cpp
+++ b/Source/modules/performance/WorkerPerformance.cpp
@@ -31,6 +31,7 @@
 #include "config.h"
 #include "modules/performance/WorkerPerformance.h"
 
+#include "core/timing/MemoryInfo.h"
 #include "core/workers/DedicatedWorkerGlobalScope.h"
 #include "core/workers/WorkerGlobalScope.h"
 #include "wtf/CurrentTime.h"
@@ -54,4 +55,10 @@ double WorkerPerformance::now(ExecutionContext* context) const
     return 1000.0 * (monotonicallyIncreasingTime() - workerGlobalScope->timeOrigin());
 }
 
+PassRefPtrWillBeRawPtr<MemoryInfo> WorkerPerformance::memory() const
+{
+    // FIXME: We shall not create a new object every time.
+    return MemoryInfo::create();
+}
+
 } // namespace WebCore