Migrate WTF::HashMap::get() to ::at()

third_party/WebKit/Source/wtf/HashCountedSet.h

Index: third_party/WebKit/Source/wtf/HashCountedSet.h
diff --git a/third_party/WebKit/Source/wtf/HashCountedSet.h b/third_party/WebKit/Source/wtf/HashCountedSet.h
index 4815a6e2b9f9490f4a2f31c11cb13ff0850158aa..6d99b5fc71aca86cf385f7f8bcf21c2210367a29 100644
--- a/third_party/WebKit/Source/wtf/HashCountedSet.h
+++ b/third_party/WebKit/Source/wtf/HashCountedSet.h
@@ -81,7 +81,7 @@ class HashCountedSet {
     return m_impl.find(value);
   }
   bool contains(const ValueType& value) const { return m_impl.contains(value); }
-  unsigned count(const ValueType& value) const { return m_impl.get(value); }
+  unsigned count(const ValueType& value) const { return m_impl.at(value); }
 
   // Increases the count if an equal value is already present the return value
   // is a pair of an iterator to the new value's location, and a bool that is