Provide a std::vector compliant empty() method for WebVector.

third_party/WebKit/public/platform/WebVector.h

Index: third_party/WebKit/public/platform/WebVector.h
diff --git a/third_party/WebKit/public/platform/WebVector.h b/third_party/WebKit/public/platform/WebVector.h
index 533770c6953e4e12071b24a470657f8524c1d2a4..f3be46fd39adf827badec1dca5c76966e62c51ae 100644
--- a/third_party/WebKit/public/platform/WebVector.h
+++ b/third_party/WebKit/public/platform/WebVector.h
@@ -111,7 +111,9 @@ class WebVector {
   }
 
   size_t size() const { return m_data.size(); }
-  bool isEmpty() const { return m_data.empty(); }
+  bool empty() const { return m_data.empty(); }
+  // TODO(slangley): Remove all uses of isEmpty.
+  bool isEmpty() const { return empty(); }
 
   T& operator[](size_t i) {
     DCHECK_LT(i, m_data.size());