Invalidate the previous caret location when editing text nodes.

third_party/WebKit/LayoutTests/paint/invalidation/invalidate-caret-before-text-node-update.html

+<script src="../../resources/testharness.js"></script>
+<div contenteditable id="root" class="editing">
+<span id="test"></span>
+</div>
+<pre id="output">

[yosin_UTC9, 2016/04/30 03:16:17]

nit: Pleas use <div id="log"></div>, if so you don't need to have *-expected.txt

[chrishtr, 2016/04/30 21:56:30]

Done.

+<pre>
+<script>
+if (window.testRunner)

[yosin_UTC9, 2016/04/30 03:16:16]

You don't need to have this if-statement, w3c test harness automatically does
so.

[chrishtr, 2016/04/30 21:56:30]

Done.

+        window.testRunner.dumpAsText();
+
+test(function editingTest() {

[yosin_UTC9, 2016/04/30 03:16:17]

s/test(function editingTest() {/test(function() {/

+        // The innerText must be set explicitly, and not with an editing command.
+        root.innerText = "1";
+        window.getSelection().collapse(root.firstChild, 1);
+
+        if (window.internals)
+            window.internals.startTrackingRepaints(document);
+
+        document.execCommand('delete');
+
+        if (window.internals) {
+                var layers = JSON.parse(window.internals.layerTreeAsText(document, internals.LAYER_TREE_INCLUDES_PAINT_INVALIDATIONS));
+                assert_true(layers.children[0].paintInvalidations[2].reason == "invalidate paint rectangle");

[yosin_UTC9, 2016/04/30 03:16:17]

Please use assert_equal(actual, expected, [description])
See https://github.com/w3c/testharness.js/blob/master/docs/api.md

+                // Check that thet x offset is 22. This for the caret rect before delete.
+                assert_true(layers.children[0].paintInvalidations[2].rect[3] == 22);

[yosin_UTC9, 2016/04/30 03:16:16]

Please use assert_equal(actual, expected)

[chrishtr, 2016/04/30 21:56:30]

Done.

+                assert_true(layers.children[0].paintInvalidations[3].reason == "invalidate paint rectangle");

[yosin_UTC9, 2016/04/30 03:16:17]

Please use assert_equal(actual, expected)

[chrishtr, 2016/04/30 21:56:30]

Done.

+                // Check that thet x offset is 22. This for the caret rect after delete.
+                assert_true(layers.children[0].paintInvalidations[3].rect[3] == 21);

[yosin_UTC9, 2016/04/30 03:16:17]

Please use assert_equal(actual, expected)

[chrishtr, 2016/04/30 21:56:30]

Done.

+         }
+});
+

[yosin_UTC9, 2016/04/30 03:16:16]

nit: No need to have extra blank lines.

+
+</script>