Add tab characters support in complex path

Source/platform/fonts/shaping/HarfBuzzShaper.cpp

 /*
  * Copyright (c) 2012 Google Inc. All rights reserved.
  * Copyright (C) 2013 BlackBerry Limited. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 1122 matching lines @@
         result->m_glyphBoundingBox.unite(glyphBounds);
         glyphOrigin += FloatSize(advance + offsetX, offsetY);
     }
 
     run->m_width = totalAdvance > 0.0 ? totalAdvance : 0.0;
     result->m_width += run->m_width;
     result->m_numGlyphs += numGlyphs;
     result->m_runs[index] = run.release();
 }
 
+PassRefPtr<ShapeResult> ShapeResult::createForTabulationCharacters(const Font* font,
+    const TextRun& textRun, float positionOffset, unsigned count)
+{
+    const SimpleFontData* fontData = font->primaryFont();
+    OwnPtr<ShapeResult::RunInfo> run = adoptPtr(new ShapeResult::RunInfo(fontData,
+        // Tab characters are always LTR or RTL, not TTB, even when isVerticalAnyUpright().
+        textRun.rtl() ? HB_DIRECTION_RTL : HB_DIRECTION_LTR,
+        HB_SCRIPT_COMMON, 0, count, count));
+    float position = textRun.xPos() + positionOffset;
+    float startPosition = position;
+    for (unsigned i = 0; i < count; i++) {
+        float advance = font->tabWidth(*fontData, textRun.tabSize(), position);
+        run->m_glyphData[i].characterIndex = i;
+        run->setGlyphAndPositions(i, fontData->spaceGlyph(), advance, 0, 0);
+        position += advance;
+    }
+    run->m_width = position - startPosition;
+
+    RefPtr<ShapeResult> result = ShapeResult::create(font, count, textRun.direction());
+    result->m_width = run->m_width;
+    result->m_numGlyphs = count;
+    result->m_runs.append(run.release());
+    return result.release();
+}
+
 float HarfBuzzShaper::adjustSpacing(ShapeResult::RunInfo* run, size_t glyphIndex, unsigned currentCharacterIndex, float& offset, float& totalAdvance)
 {
     float spacing = 0;
     UChar32 character = m_normalizedBuffer[currentCharacterIndex];
     if (m_letterSpacing && !Character::treatAsZeroWidthSpace(character))
         spacing += m_letterSpacing;
 
     bool treatAsSpace = Character::treatAsSpace(character);
     if (treatAsSpace && currentCharacterIndex && (character != '\t' || !m_textRun.allowTabs()))
         spacing += m_wordSpacingAdjustment;
@@ skipping 37 matching lines @@
             return spacing;
     }
 
     // Don't need to check m_textRun.allowsTrailingExpansion() since it's covered by !m_expansionOpportunityCount above
     spacing += nextExpansionPerOpportunity();
     m_isAfterExpansion = true;
     return spacing;
 }
 
 } // namespace blink