v-0001: Only allowed import is GLSL.std.450

Bug: tint:10

Change-Id: I566ff378c4cd72febc0a73434b5dfe1039ef2c42
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/16420
Reviewed-by: Dan Sinclair <dsinclair@google.com>
Commit-Queue: Dan Sinclair <dsinclair@google.com>
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 30b6e04..9d6cad9 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -174,6 +174,8 @@
   type_manager.h
   validator.cc
   validator.h
+  validator_impl.cc
+  validator_impl.h
   # TODO(dsinclair): The writers should all be optional
   writer/spv/generator.cc
   writer/spv/generator.h
@@ -283,6 +285,7 @@
   reader/wgsl/parser_impl_variable_storage_decoration_test.cc
   reader/wgsl/token_test.cc
   type_manager_test.cc
+  validator_impl_import_test.cc
 )
 
 ## Tint library