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 67e77e1ba13c2cfa15a2b83fbf2ef0b584fe02c7..fae13294658593286da2a3848f1455e3fe52baee 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() const
     return 1000.0 * (monotonicallyIncreasingTime() - workerGlobalScope->timeOrigin());
 }
 
+PassRefPtr<MemoryInfo> WorkerPerformance::memory() const
+{
+    ExecutionContext* context = executionContext();
+    return MemoryInfo::create(context);
+}
+
 } // namespace WebCore