Do not dispatch 'change' events during pressing spin buttons for input[type=number].

TextFieldInputType sends change event for its derived class. Change is
done for DispatchInputAndChangeEvent to behave similar to
DispatchChangeEvent.
DispatchChangeEvent is generated by Range, Radio, File and Checkbox
input type.
DispatchInputAndChangeEvent is generated by inputtype for step up and
down, BaseChooser/BaseMultipleFieldsDateandTime also generates
DispatchInputAndChangeEvent.
Since it is different set of inputs that generate DispatchChange and
DispatchInputAndChange, both are kept but behavior is changed; this
allows spin button to handle mouseup event.
Keyboard events are also handled for spin button.

R=tkent
BUG=155747
TEST=automated

Review URL: https://codereview.chromium.org/128133002

git-svn-id: svn://svn.chromium.org/blink/trunk@165300 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Remove class from code_generator_v8.py

Now that we're not generating dummy files (so we always have an interface),
we don't need a code generator class, since it's purely functional:
"Write the files for this interface."

This removes the class, reducing complexity of the CG:
remove indentation, remove |self|, remove initialization.

Followup to:
Split dependencies from built IDL files in GYP
https://codereview.chromium.org/136033011/

R=haraken
NOTRY=true

Review URL: https://codereview.chromium.org/140173005

git-svn-id: svn://svn.chromium.org/blink/trunk@165301 bbb929c8-8fbe-4397-9dbb-9b2b20218538