Web Inspector: scrollbar may appear when selecting a stop in gradient editor

Web Inspector: scrollbar may appear when selecting a stop in gradient editor
https://bugs.webkit.org/show_bug.cgi?id=129149

Reviewed by Timothy Hatcher.

Ensure the angle input is not focused as we update the size of the gradient editor's
popover content since, if it were, it'd make a scrollbar appear as we animate the
popover's frame to fit its new content.

* UserInterface/CodeMirrorGradientEditingController.js:
(WebInspector.CodeMirrorGradientEditingController.prototype.gradientSliderStopWasSelected):

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@164483 268f45cc-cd09-0410-ab3c-d52691b4dbfc