Dispatch change event for input type=color when colorpicker is closed

Change event should be trigger when colorpicker is closed. In current it dispatches for each value change in colorpicker.

In current code, JS function selectColorInColorChooser(which in turn call didChooseColor) set the color and expects dispatch change event. SetValue also calls didChooseColor. Since both JS function and setValue are calling didChooseColor, it ends up firing change event for each value change.

This CL dispatches change event from endChooserColor to solve change event not dispatched when value is set by the user. Since mac, uses non-modal window, it still dispatches change event. 

To test the functionality endColorChooser has been added to test value added, only on close of color chooser change event is dispatched.

BUG=405059
R=tkent, keishi
TEST=Updated tests to check changing color does not dispatch change event, only on closing of window it does.

Review URL: https://codereview.chromium.org/513783002

git-svn-id: svn://svn.chromium.org/blink/trunk@182433 bbb929c8-8fbe-4397-9dbb-9b2b20218538