Update brightray to get its Python scripts

* vendor/brightray 487be20...ef26220 (17):
  > Merge pull request #15 from brightray/cibuild
  > Update for libchromiumcontent repo transfer
  > Fix script/bootstrap
  > Merge pull request #12 from aroben/python
  > Merge pull request #9 from aroben/frontend-host-crash
  > Fix crashes when dragging links
  > Turn off C++ exceptions
  > Allow embedders to specify extra .pak files
  > Allow embedders to provide their own ContentClient subclass
  > Update to latest libchromiumcontent
  > Fix DCHECK() assertion in BrowserClient
  > Let embedders add their own protocol handlers
  > Pull in latest libchromiumcontent to get gtest
  > Merge pull request #8 from aroben/atom
  > Update to latest libchromiumcontent
  > Size dev tools correctly when starting out docked to the right
  > Send focus/blur events when an InspectableWebContents's window gains/loses focus
Rewrite script/bootstrap in Python

This is the first step toward supporting Windows.
Rewrite script/build in Python
Rewrite script/cibuild in Python
Merge pull request #9 from brightray/python

Rewrite scripts in Python