Add a test that we resume commits after inserting the body.

Source/core/dom/Document.cpp

Index: Source/core/dom/Document.cpp
diff --git a/Source/core/dom/Document.cpp b/Source/core/dom/Document.cpp
index f2929f0eb0859debabec50951d240a1dfae0d4b2..1d66fb41ce8cea65e207d5d0f3e36091ad434676 100644
--- a/Source/core/dom/Document.cpp
+++ b/Source/core/dom/Document.cpp
@@ -336,6 +336,8 @@ static bool acceptsEditingFocus(const Element& element)
 
 uint64_t Document::s_globalTreeVersion = 0;
 
+static bool s_threadedParsingEnabledForUnitTests = true;
+
 Document::WeakDocumentSet& Document::liveDocumentSet()
 {
     DEFINE_STATIC_LOCAL(OwnPtrWillBePersistent<WeakDocumentSet>, set, (adoptPtrWillBeNoop(new WeakDocumentSet())));
@@ -2381,6 +2383,9 @@ PassRefPtrWillBeRawPtr<DocumentParser> Document::implicitOpen(ParserSynchronizat
 
     setCompatibilityMode(NoQuirksMode);
 
+    if (!threadedParsingEnabledForUnitTestsOnly())
+        parserSyncPolicy = ForceSynchronousParsing;
+
     m_parserSyncPolicy = parserSyncPolicy;
     m_parser = createParser();
     setParsingState(Parsing);
@@ -5226,6 +5231,16 @@ void Document::adjustFloatRectForScrollAndAbsoluteZoom(FloatRect& rect, LayoutOb
     adjustFloatRectForAbsoluteZoom(rect, layoutObject);
 }
 
+void Document::setThreadedParsingEnabledForUnitTestsOnly(bool enabled)
+{
+    s_threadedParsingEnabledForUnitTests = enabled;
+}
+
+bool Document::threadedParsingEnabledForUnitTestsOnly()
+{
+    return s_threadedParsingEnabledForUnitTests;
+}
+
 bool Document::hasActiveParser()
 {
     return m_activeParserCount || (m_parser && m_parser->processingData());