Fix unit test style in core/{dom,editing,html}/.

Source/core/editing/CompositionUnderlineRangeFilterTest.cpp

Index: Source/core/editing/CompositionUnderlineRangeFilterTest.cpp
diff --git a/Source/core/editing/CompositionUnderlineRangeFilterTest.cpp b/Source/core/editing/CompositionUnderlineRangeFilterTest.cpp
index c67c6eed0b66c61457b852b4d632eb9170f0a7be..a179dda1ba7cc0deb55c0c8f7fb3f84af0f437e1 100644
--- a/Source/core/editing/CompositionUnderlineRangeFilterTest.cpp
+++ b/Source/core/editing/CompositionUnderlineRangeFilterTest.cpp
@@ -12,9 +12,7 @@
 #include "wtf/text/WTFString.h"
 #include <gtest/gtest.h>
 
-using namespace blink;
-
-namespace {
+namespace blink {
 
 // Parses test case string and populate |underlines|.
 void initUnderlines(const String& testCase, Vector<CompositionUnderline>* underlines)
@@ -87,4 +85,4 @@ TEST(CompositionUnderlineRangeFilterTest, Multi)
     EXPECT_EQ("DFG", filterUnderlines(underlines, 7, 7));
 }
 
-} // namespace
+} // namespace blink