Let's make TextInputHandler::HandleCommand() handle other
commands which are caused by Backspace, Delete, Tab, ArrowUp,
ArrowDown, ArrowRight, ArrowLeft, PageUp, PageDown, Home, End
and Escape keys with various modifiers.
This patch makes Korean users can do most key operation in
editor even with composing Hangul character.
Note that this patch has a hack for cancelOperation: command.
The command is typically fired for Escape key press. However,
it's also fired for Command + Period. Unfortunately, this
behavior is really odd if subclass of NSResponder implements
|void cancelOperation:(id)sender|. If it's implemented,
Cocoa doesn't call its |void keyDown:(NSEvent)theEvent|.
Instead, it calls only |void doCommandBySelector:(SEL)aSelector|
and |void cancelOperation:(id)sender| when Command + Period is
pressed. Therefore, we cannot dispatch keydown nor keypress
event for this key combination if we implement it. Therefore,
this patch doesn't implement the method but handle it in
doCommandBySelector even though the super class of ChildView
cannot handle the command with this path.
MozReview-Commit-ID: 4hS23SiwNJv
Currently, we handle insertNewline: of NSResponder with
TextInputHandler::InsertNewline(). However, its
implementation is useful for handling some other
commands. So, let's rename it to HandleCommand() and
make it take Command as its argument for handling
specific behavior of each command.
MozReview-Commit-ID: GgzQdTlVtYl
