Improve the find word boundary performance

In endWordBoundary case, finding start boundary in findWordBoundary is unnecessary.
So, skip it to improve the find word boundary performance.

Merge from WebKit
https://bugs.webkit.org/show_bug.cgi?id=125619

BUG= 371249

Review URL: https://codereview.chromium.org/268363016

git-svn-id: svn://svn.chromium.org/blink/trunk@178621 bbb929c8-8fbe-4397-9dbb-9b2b20218538

third_party/WebKit/Source/core/editing/VisibleUnits.cpp

@@ -653,9 +653,7 @@ static unsigned endWordBoundary(const UChar* characters, unsigned length, unsign
         return length;
     }
     needMoreContext = false;
-    int start, end;
-    findWordBoundary(characters, length, offset, &start, &end);
-    return end;
+    return findWordEndBoundary(characters, length, offset);
 }
 
 VisiblePosition endOfWord(const VisiblePosition &c, EWordSide side)

third_party/WebKit/Source/platform/text/TextBoundaries.cpp

@@ -99,5 +99,11 @@ void findWordBoundary(const UChar* chars, int len, int position, int* start, int
     *start = it->previous();
 }
 
+int findWordEndBoundary(const UChar* chars, int len, int position)
+{
+    TextBreakIterator* it = wordBreakIterator(chars, len);
+    int end = it->following(position);
+    return end < 0 ? it->last() : end;
+}
 
 } // namespace blink

third_party/WebKit/Source/platform/text/TextBoundaries.h

@@ -40,6 +40,7 @@ PLATFORM_EXPORT int endOfFirstWordBoundaryContext(const UChar* characters, int l
 PLATFORM_EXPORT int startOfLastWordBoundaryContext(const UChar* characters, int length);
 
 PLATFORM_EXPORT void findWordBoundary(const UChar*, int len, int position, int* start, int* end);
+PLATFORM_EXPORT int findWordEndBoundary(const UChar*, int len, int position);
 PLATFORM_EXPORT int findNextWordFromIndex(const UChar*, int len, int position, bool forward);
 
 }