Build CompositionUnderline information in TextInputController::setMarkedText()

TextInputController::setMarkedText(text, start, length) specifies
marked range with 2nd and 3rd parameters, but they are not reflected to
Vector<WebCompositionUnderlines> parameter for WebViewImpl::setComposition().

Build CompositionUnderline information so tests can use the infromation
(notably IME API tests will need the information).

BUG=none
TEST=all layouttests pass

Review URL: https://chromiumcodereview.appspot.com/23718008

git-svn-id: svn://svn.chromium.org/blink/trunk@157581 bbb929c8-8fbe-4397-9dbb-9b2b20218538