spirv-reader: Add entry point declaration to handle test

Bug: tint:109
Change-Id: I25645944061b8b247eda442b61f4591a9359ec4f
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/34422
Commit-Queue: David Neto <dneto@google.com>
Auto-Submit: David Neto <dneto@google.com>
Reviewed-by: Ben Clayton <bclayton@google.com>
diff --git a/src/reader/spirv/parser_impl_handle_test.cc b/src/reader/spirv/parser_impl_handle_test.cc
index 655f11b..704e654 100644
--- a/src/reader/spirv/parser_impl_handle_test.cc
+++ b/src/reader/spirv/parser_impl_handle_test.cc
@@ -1208,6 +1208,8 @@
 
 TEST_P(SpvParserTest_DeclHandle_SampledImage, Variable) {
   const auto assembly = Preamble() + R"(
+     OpEntryPoint Fragment %main "main"
+     OpExecutionMode %main OriginUpperLeft
      OpName %f1 "f1"
      OpName %vf12 "vf12"
      OpName %vf123 "vf123"