Invalidate the previous caret location when editing text nodes.

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

+<script src="../../editing/editing.js"></script>

[yosin_UTC9, 2016/04/29 15:03:12]

Could you avoid to use "editing/editing.js"?
Because of this test doesn't need to check "selectionchange" event and it makes
refactoring of FrameSeleciton harder.

[chrishtr, 2016/04/29 20:09:40]

Done.

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

[yosin_UTC9, 2016/04/29 15:03:12]

Let's use w3c test harness directly:

test(function() {
...
});

[chrishtr, 2016/04/29 20:09:40]

Done.

+        // The innerText must be set explicitly, and not with an editing command.
+        root.innerText = "1";
+        moveSelectionForwardByCharacterCommand();    

[yosin_UTC9, 2016/04/29 15:03:12]

window.getSelection().collapse(root.firstChild, 1);

[chrishtr, 2016/04/29 20:09:40]

Done.

+
+        if (window.internals)
+            window.internals.startTrackingRepaints(document);
+
+        deleteCommand();

[yosin_UTC9, 2016/04/29 15:03:12]

document.execCommand('delete');

[chrishtr, 2016/04/29 20:09:40]

Done.

+
+        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");
+                // Check that thet x offset is 22. This for the caret rect before delete.
+                assert_true(layers.children[0].paintInvalidations[2].rect[3] == 22);
+                assert_true(layers.children[0].paintInvalidations[3].reason == "invalidate paint rectangle");
+                // Check that thet x offset is 22. This for the caret rect after delete.
+                assert_true(layers.children[0].paintInvalidations[3].rect[3] == 21);
+         }
+}
+
+if (window.testRunner)
+        window.testRunner.dumpAsText();
+
+runEditingTest();
+</script>