gsk: Stop setting uniforms when we are out of batches

When the command queue is out of batches, there is
no point in doing further work like allocating uniforms.

This helps us avoid assertions in the uniform code
that we would hit when we run out of uniform space
too.

gsk/gl/gskglcommandqueue.c

@@ -579,7 +579,7 @@ discard_batch (GskGLCommandQueue *self)
   self->batches.len--;
 }
 
-void
+gboolean
 gsk_gl_command_queue_begin_draw (GskGLCommandQueue   *self,
                                  GskGLUniformProgram *program,
                                  guint                width,
@@ -596,7 +596,7 @@ gsk_gl_command_queue_begin_draw (GskGLCommandQueue   *self,
    * of batches we can have in one frame.
    */
   if (will_ignore_batch (self))
-    return;
+    return FALSE;
 
   self->program_info = program;
 
@@ -617,6 +617,8 @@ gsk_gl_command_queue_begin_draw (GskGLCommandQueue   *self,
   self->fbo_max = MAX (self->fbo_max, batch->draw.framebuffer);
 
   self->in_draw = TRUE;
+
+  return TRUE;
 }
 
 void

gsk/gl/gskglcommandqueueprivate.h

@@ -331,7 +331,7 @@ void                gsk_gl_command_queue_delete_program       (GskGLCommandQueue
 void                gsk_gl_command_queue_clear                (GskGLCommandQueue    *self,
                                                                guint                 clear_bits,
                                                                const graphene_rect_t *viewport);
-void                gsk_gl_command_queue_begin_draw           (GskGLCommandQueue    *self,
+gboolean            gsk_gl_command_queue_begin_draw           (GskGLCommandQueue    *self,
                                                                GskGLUniformProgram  *program_info,
                                                                guint                 width,
                                                                guint                 height);