Add support for shaping a substring to HarfBuzzShaper

third_party/WebKit/Source/platform/fonts/shaping/RunSegmenter.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 "platform/fonts/shaping/RunSegmenter.h"
 
 #include "platform/fonts/ScriptRunIterator.h"
 #include "platform/fonts/SmallCapsIterator.h"
 #include "platform/fonts/SymbolsIterator.h"
 #include "platform/fonts/UTF16TextIterator.h"
 #include "platform/text/Character.h"
 #include "wtf/Assertions.h"
 #include "wtf/PtrUtil.h"
 
 namespace blink {
 
 RunSegmenter::RunSegmenter(const UChar* buffer,
                            unsigned bufferSize,
                            FontOrientation runOrientation)
     : m_bufferSize(bufferSize),
-      m_candidateRange({0, 0, USCRIPT_INVALID_CODE,
-                        OrientationIterator::OrientationKeep,
-                        FontFallbackPriority::Text}),
+      m_candidateRange(nullRange()),
       m_scriptRunIterator(
           WTF::makeUnique<ScriptRunIterator>(buffer, bufferSize)),
       m_orientationIterator(
           runOrientation == FontOrientation::VerticalMixed
               ? WTF::wrapUnique(
                     new OrientationIterator(buffer, bufferSize, runOrientation))
               : nullptr),
       m_symbolsIterator(WTF::makeUnique<SymbolsIterator>(buffer, bufferSize)),
       m_lastSplit(0),
       m_scriptRunIteratorPosition(0),
@@ skipping 62 matching lines @@
 
   m_candidateRange.start = m_candidateRange.end;
   m_candidateRange.end = m_lastSplit;
   *nextRange = m_candidateRange;
 
   m_atEnd = m_lastSplit == m_bufferSize;
   return true;
 }
 
 }  // namespace blink