Allow marking expectations as INVALID.

This CL adds the ability to set the `SKIP` line in an expectation to be
`SKIP: INVALID` if the test will never pass on the given platform.

Change-Id: I8f649bb0faf89d03fbe86b5b1a00575ff91f2fd3
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/202716
Commit-Queue: dan sinclair <dsinclair@chromium.org>
Commit-Queue: Antonio Maiorano <amaiorano@google.com>
Reviewed-by: Antonio Maiorano <amaiorano@google.com>
diff --git a/test/tint/expressions/bitcast/let/32bit/vec2f16-u32.wgsl.expected.fxc.hlsl b/test/tint/expressions/bitcast/let/32bit/vec2f16-u32.wgsl.expected.fxc.hlsl
index 2332ca6..8d2c1cb 100644
--- a/test/tint/expressions/bitcast/let/32bit/vec2f16-u32.wgsl.expected.fxc.hlsl
+++ b/test/tint/expressions/bitcast/let/32bit/vec2f16-u32.wgsl.expected.fxc.hlsl
@@ -1,4 +1,4 @@
-SKIP: FAILED
+SKIP: INVALID
 
 uint tint_bitcast_from_f16(vector<float16_t, 2> src) {
   uint2 r = f32tof16(float2(src));