text-align-last only affect to the last line when text-align is justify.

Source/core/rendering/RenderBlockLineLayout.cpp

 /*
  * Copyright (C) 2000 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2003, 2004, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All right reserved.
  * Copyright (C) 2010 Google Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
@@ skipping 301 matching lines @@
 
 ETextAlign RenderBlockFlow::textAlignmentForLine(bool endsWithSoftBreak) const
 {
     ETextAlign alignment = style()->textAlign();
     if (endsWithSoftBreak)
         return alignment;
 
     if (!RuntimeEnabledFeatures::css3TextEnabled())
         return (alignment == JUSTIFY) ? TASTART : alignment;
 
+    if (alignment != JUSTIFY)
+        return alignment;
+
     TextAlignLast alignmentLast = style()->textAlignLast();
     switch (alignmentLast) {
     case TextAlignLastStart:
         return TASTART;
     case TextAlignLastEnd:
         return TAEND;
     case TextAlignLastLeft:
         return LEFT;
     case TextAlignLastRight:
         return RIGHT;
     case TextAlignLastCenter:
         return CENTER;
     case TextAlignLastJustify:
         return JUSTIFY;
     case TextAlignLastAuto:
-        if (alignment != JUSTIFY)
-            return alignment;
         if (style()->textJustify() == TextJustifyDistribute)
             return JUSTIFY;
         return TASTART;
     }
 
     return alignment;
 }
 
 static void updateLogicalWidthForLeftAlignedBlock(bool isLeftToRightDirection, BidiRun* trailingSpaceRun, float& logicalLeft, float& totalLogicalWidth, float availableLogicalWidth)
 {
@@ skipping 1832 matching lines @@
     float logicalLeft = logicalLeftOffsetForLine(logicalHeight(), false).toFloat();
     float availableLogicalWidth = logicalRightOffsetForLine(logicalHeight(), false) - logicalLeft;
     updateLogicalWidthForAlignment(textAlign, 0, 0, logicalLeft, totalLogicalWidth, availableLogicalWidth, 0);
 
     if (!style()->isLeftToRightDirection())
         return logicalWidth() - logicalLeft;
     return logicalLeft;
 }
 
 }