Replace usage of WebVector::isEmpty with WebVector::empty().

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 f3be46fd39adf827badec1dca5c76966e62c51ae..81903b2d76572c38d1365398b9703acb68feb286 100644
--- a/third_party/WebKit/public/platform/WebVector.h
+++ b/third_party/WebKit/public/platform/WebVector.h
@@ -112,8 +112,6 @@ class WebVector {
 
   size_t size() const { return m_data.size(); }
   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());