Make Document::caretRangeFromPoint() to work with :first-letter style

LayoutTests/fast/dom/Document/CaretRangeFromPoint/caretRangeFromPoint-with-first-letter-style.html

+<style>
+p.first-letter:first-letter { color: red; }
+</style>
+<div id="container">
+<p id="description"></p>
+<p id="sample" class="first-letter"><span>0123456</span></p>
+</div>
+<div id="console"></div>
+<script src="../../../../fast/js/resources/js-test-pre.js"></script>
+<script>
+description('caretRangeFromPoint() should work with :first-letter style');
+function $(id) { return document.getElementById(id); }
+
+var range;
+window.onload = function() {
+    var middle = $('sample').offsetTop + $('sample').offsetHeight / 2;
+    var left = $('sample').offsetLeft;
+    var numberOfChars = $('sample').firstChild.firstChild.length;
+    var charWidth = $('sample').firstChild.offsetWidth / numberOfChars;
+    var x = left;
+    for (var i = 0; i < numberOfChars; ++i) {
+        range = document.caretRangeFromPoint(x + 3, middle);
+        shouldBe('range.startOffset', i.toString());
+        x += charWidth;
+    }
+
+    if (window.testRunner) {
+        $('container').outerHTML = '';
+        finishJSTest();
+    }
+}
+window.jsTestIsAsync = true;

[ojan, 2013/10/04 17:36:25]

This test doesn't need to be async if you're running it during onload.

Incidentally, you also probably don't need to run it onload either. You should
be able to run it synchronously.

+</script>
+<script src="../../../../fast/js/resources/js-test-post.js"></script>