Use shouldBecomeEqual in asynchronous spellchecking tests.

LayoutTests/editing/spelling/spellcheck-paste-disabled.html

Index: LayoutTests/editing/spelling/spellcheck-paste-disabled.html
diff --git a/LayoutTests/editing/spelling/spellcheck-paste-disabled.html b/LayoutTests/editing/spelling/spellcheck-paste-disabled.html
index 89feb8ff76298c3632b077e06b72604d1fc16133..c2da7668c2be04f1a053ea4031a886ba36322825 100644
--- a/LayoutTests/editing/spelling/spellcheck-paste-disabled.html
+++ b/LayoutTests/editing/spelling/spellcheck-paste-disabled.html
@@ -14,8 +14,6 @@ description('Test if WebKit does not spellcheck text when pasting text to an ele
             'To test manually, copy the text "zz apple" and paste it to the textarea. ' +
             'When "zz" is not marked as misspelled, this test succeeds.');
 
-jsTestIsAsync = true;
-
 // Insert a misspelled word to initialize a spellchecker.
 var srcNode = document.getElementById('src');
 srcNode.focus();
@@ -31,29 +29,11 @@ shouldBeTrue('internals.hasSpellingMarker(document, 0, 2)');
 window.getSelection().selectAllChildren(srcNode);
 document.execCommand('Copy');
 
-internals.settings.setAsynchronousSpellCheckingEnabled(true);
-
 var dstNode = document.getElementById('dst');
 dstNode.focus();
 document.execCommand('Paste');
+shouldBeFalse('internals.hasSpellingMarker(document, 0, 2)');
 
-var retryCount = 10;
-var sleepPeriod = 1;
-function verifyMarker() {
-    dstNode.focus();
-    var hasMarker = internals.hasSpellingMarker(document, 0, 2);
-    if (!hasMarker && --retryCount > 0) {
-        sleepPeriod *= 2;
-        window.setTimeout(verifyMarker, sleepPeriod);
-        return;
-    }
-    if (hasMarker)
-        testFailed('The destination node should not have a marker.');
-    else
-        testPassed('The destination node does not have any markers.');
-    finishJSTest();
-}
-window.setTimeout(verifyMarker, sleepPeriod);
 </script>
 <script src="../../fast/js/resources/js-test-post.js"></script>
 </body>