spir-reader: fix tests: struct with BuiltIns must have Block

Fixes https://github.com/dneto0/spirv-samples/issues/2

Change-Id: Ie3ab62f31ba7e3d7c8d4dd56f8dc9a87046e1b92
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/73241
Auto-Submit: David Neto <dneto@google.com>
Reviewed-by: James Price <jrprice@google.com>
Kokoro: David Neto <dneto@google.com>
Commit-Queue: David Neto <dneto@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
diff --git a/src/reader/spirv/parser_impl_module_var_test.cc b/src/reader/spirv/parser_impl_module_var_test.cc
index 0b4bec4..df03435 100644
--- a/src/reader/spirv/parser_impl_module_var_test.cc
+++ b/src/reader/spirv/parser_impl_module_var_test.cc
@@ -270,6 +270,7 @@
     OpMemoryModel Logical Simple
     OpEntryPoint Vertex %main "main" %1
 
+    OpDecorate %10 Block
     OpMemberDecorate %10 0 BuiltIn Position
     OpMemberDecorate %10 1 BuiltIn PointSize
     OpMemberDecorate %10 2 BuiltIn ClipDistance
@@ -4116,6 +4117,7 @@
     OpMemoryModel Logical Simple
     OpEntryPoint Vertex %main "main" %1
 
+    OpDecorate %10 Block
     OpMemberDecorate %10 0 BuiltIn Position
     OpMemberDecorate %10 1 BuiltIn PointSize
     OpMemberDecorate %10 2 BuiltIn ClipDistance