Issue #1751 -- Remove cocoa and uikit gfx and hal support code

gfx/gl/moz.build

@@ -7,10 +7,6 @@ gl_provider = 'Null'
 
 if CONFIG['MOZ_WIDGET_TOOLKIT'] == 'windows':
     gl_provider = 'WGL'
-elif CONFIG['MOZ_WIDGET_TOOLKIT'] == 'cocoa':
-    gl_provider = 'CGL'
-elif CONFIG['MOZ_WIDGET_TOOLKIT'] == 'uikit':
-    gl_provider = 'EAGL'
 elif 'gtk' in CONFIG['MOZ_WIDGET_TOOLKIT']:
     if CONFIG['MOZ_EGL_XRENDER_COMPOSITE']:
         gl_provider = 'EGL'
@@ -23,7 +19,6 @@ if CONFIG['MOZ_GL_PROVIDER']:
 EXPORTS += [
     'DecomposeIntoNoRepeatTriangles.h',
     'EGLUtils.h',
-    'ForceDiscreteGPUHelperCGL.h',
     'GfxTexturesReporter.h',
     'GLBlitHelper.h',
     'GLConsts.h',
@@ -78,32 +73,7 @@ if CONFIG['MOZ_ENABLE_SKIA_GPU']:
         # Suppress warnings from Skia header files.
         SOURCES['SkiaGLGlue.cpp'].flags += ['-Wno-implicit-fallthrough']
 
-if gl_provider == 'CGL':
-    # These files include Mac headers that are unfriendly to unified builds
-    SOURCES += [
-        "GLContextProviderCGL.mm",
-    ]
-    EXPORTS += [
-        'GLContextCGL.h',
-        'SharedSurfaceIO.h',
-    ]
-    # SharedSurfaceIO.cpp includes MacIOSurface.h which include Mac headers
-    # which define Size and Point types in root namespace with often conflict with
-    # our own types. While I haven't actually hit this issue in the present case,
-    # it's been an issue in gfx/layers so let's not risk it.
-    SOURCES += [
-        'SharedSurfaceIO.cpp',
-    ]
-elif gl_provider == 'EAGL':
-    # These files include ObjC headers that are unfriendly to unified builds
-    SOURCES += [
-        'GLContextProviderEAGL.mm',
-    ]
-    EXPORTS += [
-        'GLContextEAGL.h',
-    ]
-
-elif gl_provider == 'GLX':
+if gl_provider == 'GLX':
     # GLContextProviderGLX.cpp needs to be kept out of UNIFIED_SOURCES
     # as it includes X11 headers which cause conflicts.
     SOURCES += [