Revert of Revert r403630 which broke parsing on some sites.

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

Index: third_party/WebKit/Source/core/html/parser/HTMLTreeBuilderSimulatorTest.cpp
diff --git a/third_party/WebKit/Source/core/html/parser/HTMLTreeBuilderSimulatorTest.cpp b/third_party/WebKit/Source/core/html/parser/HTMLTreeBuilderSimulatorTest.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..f5471c62e8e90530891672a07bb92fccacf7315f
--- /dev/null
+++ b/third_party/WebKit/Source/core/html/parser/HTMLTreeBuilderSimulatorTest.cpp
@@ -0,0 +1,72 @@
+// Copyright 2016 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 "core/html/parser/HTMLTreeBuilderSimulator.h"
+
+#include "core/html/parser/CompactHTMLToken.h"
+#include "core/html/parser/HTMLParserOptions.h"
+#include "core/html/parser/HTMLToken.h"
+#include "core/html/parser/HTMLTokenizer.h"
+#include "testing/gtest/include/gtest/gtest.h"
+#include "wtf/text/TextPosition.h"
+
+#include <memory>
+
+namespace blink {
+
+namespace {
+
+static void startTag(HTMLToken& token, const char* name)
+{
+    token.clear();
+    token.beginStartTag(name[0]);
+    size_t length = strlen(name);
+    for (size_t i = 1; i < length; ++i)
+        token.appendToName(name[i]);
+}
+
+static void simulate(HTMLTreeBuilderSimulator& simulator, HTMLToken& token, HTMLTokenizer* tokenizer)
+{
+    CompactHTMLToken compactToken(&token, TextPosition::minimumPosition());
+    simulator.simulate(compactToken, tokenizer);
+}
+
+// This is a regression test for crbug.com/542803
+TEST(HTMLTreeBuilderSimulatorTest, ChangeStateInForeignContentAtHTMLIntegrationPoint)
+{
+    HTMLParserOptions options;
+    HTMLTreeBuilderSimulator simulator(options);
+    std::unique_ptr<HTMLTokenizer> tokenizer = HTMLTokenizer::create(options);
+    HTMLToken token;
+
+    startTag(token, "svg");
+    simulate(simulator, token, tokenizer.get()); // open elements: svg
+    EXPECT_EQ(HTMLTokenizer::DataState, tokenizer->getState())
+        << "the svg start tag should have put the simulator into 'in body' "
+        << "state";
+
+    startTag(token, "title");
+    simulate(simulator, token, tokenizer.get()); // svg > title
+    EXPECT_EQ(HTMLTokenizer::DataState, tokenizer->getState())
+        << "the title start tag should not have flipped the simulator into "
+        << "RCDATA state because svg is not a HTML integration point";
+
+    startTag(token, "desc");
+    simulate(simulator, token, tokenizer.get()); // svg > title > desc
+    EXPECT_EQ(HTMLTokenizer::DataState, tokenizer->getState())
+        << "the desc tag should not have flipped the simulator into the "
+        << "any unusual state because desc parsing rules do not change state, "
+        << "despite title being a HTML integration point";
+
+    startTag(token, "title");
+    simulate(simulator, token, tokenizer.get()); // svg > title > desc > title
+    EXPECT_EQ(HTMLTokenizer::RCDATAState, tokenizer->getState())
+        << "the title start tag should have flipped the simulator into the "
+        << "RCDATA state for title, despite being in foreign content mode, "
+        << "because desc is a HTML integration point";
+}
+
+}
+
+} // namespace blink