Revert harder, removing SkTaskGroup.cpp from core temporarily.

gyp/SampleApp.gyp

 #
 {
   'variables': {
     #manually set sample_pdf_file_viewer to 1 to have the PdfViewer in SampleApp
     'sample_pdf_file_viewer%': 0,
   },
   'targets': [
     {
       'target_name': 'SampleApp',
       'type': 'executable',
       'mac_bundle' : 1,
       'include_dirs' : [
         '../src/core',
         '../src/effects', #needed for BlurMask.h
         '../src/gpu', # needed by SkLua.cpp
         '../src/images',
         '../src/lazy',
         '../gm',       # needed to pull gm.h
         '../samplecode', # To pull SampleApp.h and SampleCode.h
         '../src/pipe/utils', # For TiledPipeController
         '../src/utils/debugger',
       ],
       'includes': [
         'gmslides.gypi',
       ],
       'sources': [
+        '../src/core/SkTaskGroup.cpp',
         '../gm/gm.cpp',
         '../samplecode/GMSampleView.h',
         '../samplecode/ClockFaceView.cpp',
         '../samplecode/OverView.cpp',
         '../samplecode/OverView.h',
         '../samplecode/Sample2PtRadial.cpp',
         '../samplecode/SampleAAClip.cpp',
         '../samplecode/SampleAARects.cpp',
         '../samplecode/SampleAARectModes.cpp',
         '../samplecode/SampleAll.cpp',
@@ skipping 265 matching lines @@
         }],
       ],
       'msvs_settings': {
         'VCLinkerTool': {
           'SubSystem': '2',
         },
       },
     },
   ],
 }