Use semantic names for callbacks instead of onGestureTap

Use semantic names for callbacks instead of onGestureTap

Buttons and menu items use onPressed. Also, don't pass along the sky.Event
because that's a lower-level concept.

I've also reordered parameter lists to put the |child| argument last in a
number of places.

Also, fixed a bug where FloatingActionButton was missing syncFields.

R=ianh@google.com

Committed: https://chromium.googlesource.com/external/mojo/+/a4b84708d4d5e47094c06551fa14be7a214da58b

[Hixie, 2015-06-17 22:59:22]

lgtm

https://codereview.chromium.org/1188993003/diff/1/sky/sdk/lib/widgets/floatin...
File sky/sdk/lib/widgets/floating_action_button.dart (right):

https://codereview.chromium.org/1188993003/diff/1/sky/sdk/lib/widgets/floatin...
sky/sdk/lib/widgets/floating_action_button.dart:21: this.enabled: true,
either remove this or make it affect the UI

https://codereview.chromium.org/1188993003/diff/1/sky/sdk/lib/widgets/floatin...
sky/sdk/lib/widgets/floating_action_button.dart:33: }
call the superclass.

[abarth-chromium, 2015-06-17 23:04:05]

https://codereview.chromium.org/1188993003/diff/1/sky/sdk/lib/widgets/floatin...
File sky/sdk/lib/widgets/floating_action_button.dart (right):

https://codereview.chromium.org/1188993003/diff/1/sky/sdk/lib/widgets/floatin...
sky/sdk/lib/widgets/floating_action_button.dart:21: this.enabled: true,
On 2015/06/17 at 22:59:21, Hixie wrote:
> either remove this or make it affect the UI

Removed.

https://codereview.chromium.org/1188993003/diff/1/sky/sdk/lib/widgets/floatin...
sky/sdk/lib/widgets/floating_action_button.dart:33: }
On 2015/06/17 at 22:59:21, Hixie wrote:
> call the superclass.

Done.

[abarth-chromium, 2015-06-17 23:04:18]

Committed patchset #1 (id:1) manually as
a4b84708d4d5e47094c06551fa14be7a214da58b (presubmit successful).