CaptureMidExecutionSetup() hits an assert while capturing "World War
Doh":

  ANGLE   : FATAL: FrameCapture.cpp:2876 (CaptureMidExecutionSetup):
    ! Assert failed [[[...]]] attrib.location != -1

This is due to CaptureMidExecutionSetup() enforcing that all attributes,
including built-ins, have a location. However, in the case of "World War
Doh", the built-in 'gl_GlobalInvocationID' does not have a location.

Moving the assert to after the gl::IsBuiltInName() check allows the
capture to complete without hitting any asserts.

Bug: angleproject:4048
Test: Capture "World War Doh"
Change-Id: Ice96dec629b1477b11a710283c4ec4bf1c95c6e2
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2606807Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Cody Northrop <cnorthrop@google.com>
Commit-Queue: Tim Van Patten <timvp@google.com>