remove childrenInline & setChildrenInline

sky/tests/editing/delete_block_contents.sky

+<sky>
+<import src="../resources/chai.sky" />
+<import src="../resources/mocha.sky" />
+This test verifies that the height of an editable block remains the same after adding block elements and removing them.
+<div contenteditable="true" style="border: solid blue" id="test"></div>
+<script>
+describe("height of an editable block", function(done) {
+  it("remains the same after adding block elements and removing them", function() {
+    var elem = document.getElementById("test");
+    var originalHeight = elem.offsetHeight;
+    var d = elem.appendChild(document.createElement('div'));
+    d.appendChild(document.createTextNode('aaa'));
+    d = elem.appendChild(document.createElement('div'));
+    d.appendChild(document.createTextNode('bbb'));
+    var newHeight = elem.offsetHeight;
+
+    while (elem.firstChild) {
+       elem.removeChild(elem.firstChild);
+    }
+
+    setTimeout(function() {
+      assert.equal(elem.offsetHeight, originalHeight);
+      done();
+    });
+  });
+})
+</script>
+</sky>