nodes: bug fix: |needSplit| will be true only when |startNode|'s previous sibling exists
nodes: remove unneeded console.log
nodes: add test case Nesting.3
nodes: Add tests
Merge with master
nodes: Modified indentations
Merge pull request #23 from hajimehoshi/bugfix-nodes

nodes: bug fix: |needSplit| should be true only when |startNode|'s previous sibling exists
removeFormat: Add test expectations for "removeFormat.w3c.88" and "removeFormat.w3c.88r" with issue #24.
removeFormat: Add test expectations fro "removeFormat.w3c.nested_div_style" and similar test cases with issue #25.
removeFormat: Add test expectations for "removeFormat.w3c.140" and "removeFormat.w3c.140r"
testing: Get rid of unused comments and variables from "test_expectations.js".
editing: Introduce |EditingContext.prototype.splitNode(element, refChild)| for ease of spliting selection start.
"removeFormat" is the first client of |splitNodeLeft| via |splitTreeLeft|.
editing: Introduce |EditingContext.prototype.splitTreeLeft(treeNode, refNode)|.
removeFormat: Re-artchitecture "removeFormat" command.