Revert of Perform a microtask checkpoint for document.write('<script><\/script>')

Source/core/html/parser/HTMLScriptRunner.cpp

Index: Source/core/html/parser/HTMLScriptRunner.cpp
diff --git a/Source/core/html/parser/HTMLScriptRunner.cpp b/Source/core/html/parser/HTMLScriptRunner.cpp
index 1efcad2a0241b1de84fd00c71227a54f12af545b..871096253b10d046ba70f35ae60ed435ebeed42d 100644
--- a/Source/core/html/parser/HTMLScriptRunner.cpp
+++ b/Source/core/html/parser/HTMLScriptRunner.cpp
@@ -286,7 +286,12 @@
         if (!scriptLoader)
             return;
 
-        Microtask::performCheckpoint();
+        // FIXME: This may be too agressive as we always deliver mutations at
+        // every script element, even if it's not ready to execute yet. There's
+        // unfortuantely no obvious way to tell if prepareScript is going to
+        // execute the script from out here.
+        if (!isExecutingScript())
+            Microtask::performCheckpoint();
 
         InsertionPointRecord insertionPointRecord(m_host->inputStream());
         NestingLevelIncrementer nestingLevelIncrementer(m_scriptNestingLevel);