Fix some tests and do some cleanup.

test/passthrough.inx

@@ -0,0 +1,7 @@
+vertex main :: (pos : float3 @position) -> float3 @position {
+	return pos;
+}
+
+pixel main :: () -> float4 @target0 {
+	return float4(1.0, 1.0, 1.0, 1.0);
+}