Use only external surface dimensions.

They should always be identical to the internal ones.

Bug 21424351

Change-Id: Iafa18c14cc4d2e16f20238dac0208a8159cbaa6a
Reviewed-on: https://swiftshader-review.googlesource.com/3460
Reviewed-by: Nicolas Capens <capn@google.com>
Tested-by: Nicolas Capens <capn@google.com>
diff --git a/src/Main/FrameBuffer.cpp b/src/Main/FrameBuffer.cpp
index a2f9d52..59543ac 100644
--- a/src/Main/FrameBuffer.cpp
+++ b/src/Main/FrameBuffer.cpp
@@ -124,8 +124,8 @@
 			cursor = cursorImage->lockExternal(0, 0, 0, sw::LOCK_READONLY, sw::PUBLIC);
 			cursorImage->unlockExternal();
 
-			cursorWidth = cursorImage->getExternalWidth();
-			cursorHeight = cursorImage->getExternalHeight();
+			cursorWidth = cursorImage->getWidth();
+			cursorHeight = cursorImage->getHeight();
 		}
 		else
 		{