Revert "Disable GLSL validation in E2E test runner"

This reverts commit e225232b96806717c034c81489ed39c09eecceba.

Reason for revert: breaks generating exception files.

Original change's description:
> Disable GLSL validation in E2E test runner
>
> Currently the GLSL validation takes about an hour longer for certain bot
> configurations then other validation. This CL removes the validation of
> GLSL from the test runner in order to speed up bots.
>
> A new GLSL test runner will be added which should but it back in line
> with other validation programs.
>
> Change-Id: Id6e4c0120dee5fb1ff7a03be9b42703d545a111c
> Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/147242
> Kokoro: Kokoro <noreply+kokoro@google.com>
> Reviewed-by: Ben Clayton <bclayton@google.com>
> Commit-Queue: Dan Sinclair <dsinclair@chromium.org>

# Not skipping CQ checks because original CL landed > 1 day ago.

Change-Id: If74e7a1ad5e7ba0d5a906fd7ee7699dc37433cd0
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/148020
Reviewed-by: Dan Sinclair <dsinclair@chromium.org>
Commit-Queue: Dan Sinclair <dsinclair@chromium.org>
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: Ben Clayton <bclayton@google.com>
diff --git a/tools/src/cmd/test-runner/main.go b/tools/src/cmd/test-runner/main.go
index fe20ed5..2046a22 100644
--- a/tools/src/cmd/test-runner/main.go
+++ b/tools/src/cmd/test-runner/main.go
@@ -621,8 +621,8 @@
 		case wgsl:
 			args = append(args, "--validate") // wgsl validation uses Tint, so is always available
 			validate = true
-		case spvasm:
-			args = append(args, "--validate") // spirv-val is statically linked, always available
+		case spvasm, glsl:
+			args = append(args, "--validate") // spirv-val and glslang are statically linked, always available
 			validate = true
 		case hlslDXC:
 			if cfg.dxcPath != "" {
@@ -639,9 +639,6 @@
 				args = append(args, "--xcrun", cfg.xcrunPath)
 				validate = true
 			}
-		case glsl:
-			validate = false
-			// Do nothing for now, will fill in later with validator
 		default:
 			panic("unknown format: " + j.format)
 		}