translator: Return null uniform map if no HLSL.

This replaces the global empty map.

BUG=angleproject:1459

Change-Id: If7d824cbf4492e722cbf99d1045402a26535af5c
Reviewed-on: https://chromium-review.googlesource.com/394236
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>
diff --git a/src/compiler/translator/ShaderLang.cpp b/src/compiler/translator/ShaderLang.cpp
index b6db0f0..37b1114 100644
--- a/src/compiler/translator/ShaderLang.cpp
+++ b/src/compiler/translator/ShaderLang.cpp
@@ -405,7 +405,6 @@
 
     return translator->getUniformRegisterMap();
 #else
-    static std::map<std::string, unsigned int> map;
-    return &map;
+    return nullptr;
 #endif  // ANGLE_ENABLE_HLSL
 }