Revert of SegmentedString::push() should always push a char in front (patchset...

Revert of SegmentedString::push() should always push a char in front (patchset #2 id:20001 of https://codereview.chromium.org/1308573006/ )

Reason for revert:
HTMLEntityParserTest.ConsumeHTMLEntityIncomplete fails on two Win bots

The newly added test is failing on WebKit Win7 (dbg) and WebKit Win Oilpan
(dbg) with the following message:

[ RUN      ] HTMLEntityParserTest.ConsumeHTMLEntityIncomplete
ASSERTION FAILED: !notEnoughCharacters

Sorry for the revert! Full output @ http://goo.gl/tnYH67

Original issue's description:
> SegmentedString::push() should always push a char in front
> 
> Before this CL, SegmentedString::push() had an exotic behavior, where
> two consecutive push would swap its order.
> 
> This CL changes the push() implementation so that it would always push
> the new char in front of the SegmentedString.
> This CL also updates the HTMLEntityParser code which relied on the behavior.
> 
> BUG=None
> TEST={SegmentedStringTest,HTMLEntityParserTest}.*
> 
> Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=201294

TBR=tasak@google.com,tzik@chromium.org,tkent@chromium.org,yosin@chromium.org,kouhei@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=None

Review URL: https://codereview.chromium.org/1311043004

git-svn-id: svn://svn.chromium.org/blink/trunk@201318 bbb929c8-8fbe-4397-9dbb-9b2b20218538

third_party/WebKit/Source/core/core.gypi

@@ -3814,7 +3814,6 @@
             'html/TimeRangesTest.cpp',
             'html/canvas/CanvasFontCacheTest.cpp',
             'html/forms/FileInputTypeTest.cpp',
-            'html/parser/HTMLEntityParserTest.cpp',
             'html/parser/HTMLParserThreadTest.cpp',
             'html/parser/HTMLPreloadScannerTest.cpp',
             'html/parser/HTMLResourcePreloaderTest.cpp',

third_party/WebKit/Source/core/html/parser/HTMLEntityParser.cpp

@@ -95,8 +95,8 @@ static void unconsumeCharacters(SegmentedString& source, ConsumedCharacterBuffer
     if (consumedCharacters.size() == 1)
         source.push(consumedCharacters[0]);
     else if (consumedCharacters.size() == 2) {
-        source.push(consumedCharacters[1]);
         source.push(consumedCharacters[0]);
+        source.push(consumedCharacters[1]);
     } else
         source.prepend(SegmentedString(String(consumedCharacters)));
 }
@@ -212,8 +212,8 @@ bool consumeHTMLEntity(SegmentedString& source, DecodedHTMLEntity& decodedEntity
                 entityState = Hex;
                 continue;
             }
-            source.push('x');
             source.push('#');
+            source.push('x');
             return false;
         }
         case MaybeHexUpperCaseX: {
@@ -221,8 +221,8 @@ bool consumeHTMLEntity(SegmentedString& source, DecodedHTMLEntity& decodedEntity
                 entityState = Hex;
                 continue;
             }
-            source.push('X');
             source.push('#');
+            source.push('X');
             return false;
         }
         case Hex: {

third_party/WebKit/Source/core/html/parser/HTMLEntityParser.h

@@ -27,7 +27,6 @@
 #ifndef HTMLEntityParser_h
 #define HTMLEntityParser_h
 
-#include "core/CoreExport.h"
 #include "platform/text/SegmentedString.h"
 #include "wtf/Allocator.h"
 
@@ -64,11 +63,11 @@ public:
     UChar data[kMaxLength];
 };
 
-CORE_EXPORT bool consumeHTMLEntity(SegmentedString&, DecodedHTMLEntity& decodedEntity, bool& notEnoughCharacters, UChar additionalAllowedCharacter = '\0');
+bool consumeHTMLEntity(SegmentedString&, DecodedHTMLEntity& decodedEntity, bool& notEnoughCharacters, UChar additionalAllowedCharacter = '\0');
 
 // Used by the XML parser.  Not suitable for use in HTML parsing.  Use consumeHTMLEntity instead.
 size_t decodeNamedEntityToUCharArray(const char*, UChar result[4]);
 
-} // namespace blink
+}
 
 #endif

third_party/WebKit/Source/core/html/parser/HTMLEntityParserTest.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 "config.h"
-#include "core/html/parser/HTMLEntityParser.h"
-
-#include <gtest/gtest.h>
-
-namespace blink {
-
-TEST(HTMLEntityParserTest, ConsumeHTMLEntityIncomplete)
-{
-    String original("am"); // Incomplete by purpose.
-    SegmentedString src(original);
-
-    DecodedHTMLEntity entity;
-    bool notEnoughCharacters;
-    bool success = consumeHTMLEntity(src, entity, notEnoughCharacters);
-    EXPECT_TRUE(notEnoughCharacters);
-    EXPECT_FALSE(success);
-
-    // consumeHTMLEntity should recover the original SegmentedString state if failed.
-    EXPECT_STREQ(original.ascii().data(), src.toString().ascii().data());
-}
-
-} // namespace blink

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

@@ -190,15 +190,13 @@ public:
 
     void push(UChar c)
     {
-        ASSERT(c);
-
         if (!m_pushedChar1) {
-            m_currentChar = m_pushedChar1 = c;
+            m_pushedChar1 = c;
+            m_currentChar = m_pushedChar1 ? m_pushedChar1 : m_currentString.getCurrentChar();
             updateSlowCaseFunctionPointers();
         } else {
             ASSERT(!m_pushedChar2);
-            m_pushedChar2 = m_pushedChar1;
-            m_currentChar = m_pushedChar1 = c;
+            m_pushedChar2 = c;
         }
     }
 

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

@@ -47,18 +47,20 @@ TEST(SegmentedStringTest, CurrentChar)
         EXPECT_EQ('c', copied.currentChar());
         EXPECT_EQ('c', assigned.currentChar());
     }
-    original.push('b');
+    original.push('a');
     {
         SegmentedString copied(original);
         SegmentedString assigned;
         assigned = original;
-        EXPECT_EQ("bcde", original.toString());
-        EXPECT_EQ('b', original.currentChar());
-        EXPECT_EQ('b', copied.currentChar());
-        EXPECT_EQ('b', assigned.currentChar());
+        EXPECT_EQ("acde", original.toString());
+        EXPECT_EQ('a', original.currentChar());
+        EXPECT_EQ('a', copied.currentChar());
+        EXPECT_EQ('a', assigned.currentChar());
     }
-    original.push('a');
+    original.push('b');
     {
+        // Two consecutive push means to push the second char *after* the
+        // first char in SegmentedString.
         SegmentedString copied(original);
         SegmentedString assigned;
         assigned = original;