Add a dummy implementation of a new WebWidget::confirmComposition() method.

Add a dummy implementation of a new WebWidget::confirmComposition() method.

In order to fix https://bugs.webkit.org/show_bug.cgi?id=51693, I'm going
to add following new method into WebKit::WebWidget interface:

bool confirmComposition(const WebString& text) = 0;

As PepperWidget implements WebKit::WebWidget interface directly, we need
to add a dummy implementation of this new method into PepperWidget
first to prevent chromium build from being broken.

BUG=none
TEST=none

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=70289

[Mihai Parparita -not on Chrome, 2010-12-29 23:53:02]

LGTM