Adding text node to text transformed absolute makes width wrong.

When a new RenderText is created,NodeRenderingContext::
createRendererForTextIfNeeded() sets a style to the RenderText. If the
text will be text-transformed, styleDidChange() calls
transformText(). It sets a preferredLogicalWidthsDirty flag. After that,
createRendererForTextIfNeeded() inserts the RenderText to its parent
renderer. However, RenderObjectChildList::insertChildNode() doesn't set
a preferredLogicalWidthsDirty flag of owner because a
preferredLogicalWidthsDirty flag of the RenderText is already true.

To avoid that,  setText(), which is called by transformText(), set the
preferredLogicalWidthsDirty flag only if the RenderText has a parent.

BUG=329438

Review URL: https://codereview.chromium.org/117993002

git-svn-id: svn://svn.chromium.org/blink/trunk@165732 bbb929c8-8fbe-4397-9dbb-9b2b20218538