Route selection bounds updates through WebLayerTreeView

Source/web/tests/data/composited_selection_bounds_split_layer.html

+<style>
+    @font-face {
+        font-family: ahem;
+        src: url(Ahem.ttf);
+    }
+
+    * {
+        font-family: ahem;
+    }
+
+    .composited {
+        transform: translateZ(0);
+    }
+</style>
+<div id="layer1" class="composited">The quick brown fox</div>
+<div id="layer2" class="composited">jumped over the lazy dog.</div>
+<script>
+    var range = document.createRange();
+    var layer1 = document.getElementById("layer1");
+    var textNode1 = layer1.firstChild;
+    range.setStart(textNode1, 5);
+    var layer2 = document.getElementById("layer2");
+    var textNode2 = layer2.firstChild;
+    range.setEnd(textNode2, 10);
+    document.getSelection().addRange(range);
+
+    window.expectedResult = [layer1, 60, 0, 60, 12, layer2, 120, 0, 120, 12];
+</script>
+