Add fix storage class code. (#2434)

This pass tries to fix validation error due to a mismatch of storage classes
in instructions.  There is no guarantee that all such error will be fixed,
and it is possible that in fixing these errors, it could lead to other
errors.

Fixes #2430.
diff --git a/BUILD.gn b/BUILD.gn
index 5aa1af8..8367a39 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -502,6 +502,8 @@
     "source/opt/eliminate_dead_members_pass.h",
     "source/opt/feature_manager.cpp",
     "source/opt/feature_manager.h",
+    "source/opt/fix_storage_class.cpp",
+    "source/opt/fix_storage_class.h",
     "source/opt/flatten_decoration_pass.cpp",
     "source/opt/flatten_decoration_pass.h",
     "source/opt/fold.cpp",