Plumb selection bounds as a single unit

Source/web/tests/data/composited_selection_bounds_editable.html

Index: Source/web/tests/data/composited_selection_bounds_editable.html
diff --git a/Source/web/tests/data/composited_selection_bounds_editable.html b/Source/web/tests/data/composited_selection_bounds_editable.html
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index 0000000000000000000000000000000000000000..a2e4ba4a28ba8ef1a5737e865625e8b7a972ade1
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+++ b/Source/web/tests/data/composited_selection_bounds_editable.html
@@ -0,0 +1,21 @@
+<style>
+    @font-face {
+        font-family: ahem;
+        src: url(Ahem.ttf);
+    }
+    * {
+        font-family: ahem;
+    }
+</style>
+<textarea id="text">

[Rick Byers, 2015/03/12 19:29:22]

Are <textarea> and <input type=text> similar enough that it's OK to test only
one?

I think we probably need a test case for contentEditable (see
https://developer.mozilla.org/en-US/docs/Web/Guide/HTML/Content_Editable).

[jdduke (slow), 2015/03/16 18:15:41]

Good call, I'll add one.

+    The quick brown fox jumped over the lazy dog.
+</textarea>
+<script>
+    var textNode = document.getElementById("text");
+    textNode.focus();
+
+    var expectEditable = true;
+    var expectEmptyEditable = false;
+    window.expectedResult = [document, 11, 11, 11, 25, document, 11, 11, 11, 25, expectEditable, expectEmptyEditable];
+</script>
+