A previous change broke some backward-compatibility with RowHoverEvent (issue1637803)

[is...@google.com]

Reviewers: jlabanca,

Description:
A previous change broke some backward-compatibility with RowHoverEvent
(events did not fire when expected). This change fixes the compatibility
issue, clarifies the event's scope and introduces a new field in the
event
(hovering scope).

Clients can use this field to differentiate between hover events on the
same
row and hovering between different rows, allowing more control on the
event's
processing.

Review by: pengz...@google.com

Please review this at http://gwt-code-reviews.appspot.com/1637803/

Affected files:
M user/src/com/google/gwt/user/cellview/client/AbstractCellTable.java
M user/src/com/google/gwt/user/cellview/client/RowHoverEvent.java

[jlab...@google.com]

LGTM

http://gwt-code-reviews.appspot.com/1637803/