Comment 2 for bug 1378627

StacktraceTop:
 get_stencil_miptree (irb=<optimized out>) at ../../../../../../../src/mesa/drivers/dri/i965/brw_misc_state.c:225
 brw_workaround_depthstencil_alignment (brw=0x10bb12cc8028, clear_mask=clear_mask@entry=50) at ../../../../../../../src/mesa/drivers/dri/i965/brw_misc_state.c:241
 brw_clear (ctx=0x10bb12cc8028, mask=50) at ../../../../../../../src/mesa/drivers/dri/i965/brw_clear.c:235
 gpu::gles2::GLES2DecoderImpl::Initialize (this=0x10bb11cb8f00, surface=..., context=..., offscreen=<optimized out>, size=..., disallowed_features=..., attribs=...) at ../../gpu/command_buffer/service/gles2_cmd_decoder.cc:2633
 content::GpuCommandBufferStub::OnInitialize (this=this@entry=0x10bb12d04e00, shared_state_handle=..., reply_message=0x10bb11ccbdc0) at ../../content/common/gpu/gpu_command_buffer_stub.cc:537