[spirv][ir] Add  some missing decorations.

This CL adds the `coherent` annotation to variables and function
parameters where needed. The `NonWritable` and `NonReadable` annotations
are also added to function parameters.

Change-Id: I93fdffa2c40f8bcccfa50b744ad30880d1d1e2b5
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/203294
Reviewed-by: James Price <jrprice@google.com>
Commit-Queue: dan sinclair <dsinclair@chromium.org>
diff --git a/test/tint/builtins/gen/literal/textureLoad/620caa.wgsl.expected.spvasm b/test/tint/builtins/gen/literal/textureLoad/620caa.wgsl.expected.spvasm
index c7ab6c8..0ecc5bb 100644
--- a/test/tint/builtins/gen/literal/textureLoad/620caa.wgsl.expected.spvasm
+++ b/test/tint/builtins/gen/literal/textureLoad/620caa.wgsl.expected.spvasm
@@ -31,6 +31,7 @@
                OpDecorate %tint_symbol_1 Block
                OpDecorate %1 DescriptorSet 0
                OpDecorate %1 Binding 0
+               OpDecorate %1 Coherent
                OpDecorate %arg_0 DescriptorSet 1
                OpDecorate %arg_0 Binding 0
                OpDecorate %arg_0 NonWritable