Support performance.now() in workers.

Source/modules/performance/WorkerPerformance.cpp

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 11 matching lines @@
  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #include "config.h"
-#include "core/html/ime/Composition.h"
+#include "modules/performance/WorkerPerformance.h"
 
-#include "core/dom/Node.h"
-#include "core/dom/Range.h"
+#include "core/workers/DedicatedWorkerContext.h"
+#include "core/workers/WorkerContext.h"
+#include "wtf/CurrentTime.h"
 
 namespace WebCore {
 
-Composition::~Composition()
+WorkerPerformance::WorkerPerformance(WorkerContext* context)
+    : m_context(context)
 {
 }
 
-PassRefPtr<Composition> Composition::create(Node* text, Range* caret)
+WorkerPerformance::~WorkerPerformance()
 {
-    return adoptRef(new Composition(text, caret));
 }
 
-Composition::Composition(Node* text, Range* caret)
-    : m_text(text)
-    , m_caret(caret)
+double WorkerPerformance::now() const
 {
-    ScriptWrappable::init(this);
+    return 1000.0 * (monotonicallyIncreasingTime() - m_context->timeOrigin());
 }
 
 } // namespace WebCore