Reduce allocation size of FormData::m_entries.

Source/core/html/FormDataTest.cpp

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "config.h"
 #include "core/html/FormData.h"
 
 #include <gtest/gtest.h>
 
 namespace blink {
 
 TEST(FormDataTest, opacityGet)
 {
     FormData* fd = FormData::create(UTF8Encoding());
     fd->append("name1", "value1");
 
     FileOrUSVString result;
     fd->get("name1", result);
     EXPECT_TRUE(result.isUSVString());
     EXPECT_EQ("value1", result.getAsUSVString());
 
-    const FormData::Entry& entry = fd->entries()[0];
+    const FormData::Entry& entry = *fd->entries()[0];
     EXPECT_STREQ("name1", entry.key().data());
     EXPECT_STREQ("value1", entry.data().data());
 
     fd->makeOpaque();
 
     // Web-exposed interface should be opaque.
     FileOrUSVString opaqueResult;
     fd->get("name1", opaqueResult);
     EXPECT_TRUE(opaqueResult.isNull());
 
     // Internal interface should be uneffected.
-    const FormData::Entry& entry2 = fd->entries()[0];
+    const FormData::Entry& entry2 = *fd->entries()[0];
     EXPECT_STREQ("name1", entry2.key().data());
     EXPECT_STREQ("value1", entry2.data().data());
 }
 
 TEST(FormDataTest, opacityGetAll)
 {
     FormData* fd = FormData::create(UTF8Encoding());
     fd->append("name1", "value1");
 
     HeapVector<FormDataEntryValue> results = fd->getAll("name1");
@@ skipping 24 matching lines @@
     fd->makeOpaque();
 
     // Web-exposed interface should be opaque.
     EXPECT_FALSE(fd->has("name1"));
 
     // Internal collection should be uneffected.
     EXPECT_EQ(1u, fd->size());
 }
 
 } // namespace blink