Expose performance.memory in workers

Source/modules/performance/WorkerPerformance.h

Index: Source/modules/performance/WorkerPerformance.h
diff --git a/Source/modules/performance/WorkerPerformance.h b/Source/modules/performance/WorkerPerformance.h
index 5437473cfa736e7989178f82665c03b0950db207..e7ab2356f0af3490fc33d4f1f1ea1e710ab9ac04 100644
--- a/Source/modules/performance/WorkerPerformance.h
+++ b/Source/modules/performance/WorkerPerformance.h
@@ -41,6 +41,7 @@
 namespace WebCore {
 
 class ExecutionContext;
+class MemoryInfo;
 
 class WorkerPerformance : public GarbageCollectedFinalized<WorkerPerformance>, public ScriptWrappable {
 public:
@@ -51,6 +52,7 @@ public:
     ~WorkerPerformance();
 
     double now(ExecutionContext*) const;
+    PassRefPtrWillBeRawPtr<MemoryInfo> memory() const;
 
     void trace(Visitor*) { }