conform: Do not resize the stage

Since all conformance tests share the same state we should not touch
stuff like the stage size; sharing is already fairly complex and adds a
lot of caveats on the implementation of a conformance test unit, and if
we make tests influence later ones then we might slip in bugs or false
negatives - thus defeating the whole point of a conformance test suite.

tests/conform/test-cogl-offscreen.c

@@ -144,7 +144,6 @@ test_cogl_offscreen (TestConformSimpleFixture *fixture,
 
   stage = clutter_stage_get_default ();
   clutter_stage_set_color (CLUTTER_STAGE (stage), &stage_color);
-  clutter_actor_set_size (stage, FRAMEBUFFER_WIDTH, FRAMEBUFFER_HEIGHT);
 
   /* We force continuous redrawing of the stage, since we need to skip
    * the first few frames, and we wont be doing anything else that

tests/conform/test-cogl-readpixels.c

@@ -126,7 +126,6 @@ test_cogl_readpixels (TestConformSimpleFixture *fixture,
 
   stage = clutter_stage_get_default ();
   clutter_stage_set_color (CLUTTER_STAGE (stage), &stage_color);
-  clutter_actor_set_size (stage, FRAMEBUFFER_WIDTH, FRAMEBUFFER_HEIGHT);
 
   /* We force continuous redrawing of the stage, since we need to skip
    * the first few frames, and we wont be doing anything else that

tests/conform/test-cogl-viewport.c

@@ -393,7 +393,6 @@ test_cogl_viewport (TestConformSimpleFixture *fixture,
 
   stage = clutter_stage_get_default ();
   clutter_stage_set_color (CLUTTER_STAGE (stage), &stage_color);
-  clutter_actor_set_size (stage, FRAMEBUFFER_WIDTH, FRAMEBUFFER_HEIGHT);
 
   /* We force continuous redrawing of the stage, since we need to skip
    * the first few frames, and we wont be doing anything else that

tests/conform/test-pick.c

@@ -127,7 +127,6 @@ test_pick (TestConformSimpleFixture *fixture,
 
   state.stage = clutter_stage_get_default ();
 
-  clutter_actor_set_size (state.stage, STAGE_WIDTH, STAGE_HEIGHT);
   state.actor_width = STAGE_WIDTH / ACTORS_X;
   state.actor_height = STAGE_HEIGHT / ACTORS_Y;