IDL compiler: Consolidate test IDL files

To facilitate reviewing, we want to minimize the number of test IDL files.
This consolidates IDL files in a few ways, removing 7 of 30 files:

* Consolidate most interface extended attributes into TestInterfacePython.idl
* Some interface extended attributes overlap;
  the overlapping ones are put into TestInterfacePython2.idl
* Interface extended attributes that also have content (that affect
  attributes and methods) are put in separate files, to keep these effects
  clear and separate -- this is currently just 2:
TestInterfaceCheckSecurity.idl
TestInterfaceDoNotCheckConstants.idl

I'll use this format for future interface extended attributes, meaning:
TestInterfacePython.idl if possible, others if necessary (as above).

Also:
* Delete TestSerializedScriptValueInterface.idl, as that's covered in
  TestObjectPython.idl (nothing interface-specific).
* Merge TestConstants.idl into TestObjectPython.idl.

It also renames for consistency:
Test*Interface.idl => TestInterface*.idl
(better collation).

Once I'm finished with the rewrite, I'll go through the test cases again
and see if we can consolidate or eliminate further.

NOTRY=true

Review URL: https://codereview.chromium.org/101403002

git-svn-id: svn://svn.chromium.org/blink/trunk@163135 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Drop "only composite opacity animations when already in compositing mode".

This CL fixes a bug caused by incomplete memory optimization made in r162118.
r162118 logic causes a complicated bug. When there is webkit-transform animation as
well as opacity animation, and it is not in compositing mode, it is possible
for Blink to handle opacity animation incorrectly, because Blink expects opacity
animation is accelerated. It can be fixed, but code would be more complicated,
so this CL drops this incomplete memory optimization.

BUG=324685
TEST=transitions/opacity-transform-transitions-inside-iframe.html

Review URL: https://codereview.chromium.org/101623002

git-svn-id: svn://svn.chromium.org/blink/trunk@163136 bbb929c8-8fbe-4397-9dbb-9b2b20218538