Defer asking for the TypeRegistry in ReplaceCssName till it is actual…

…ly needed.

In my tests this saves 12ms in my minimal build test, which doesn't do type checking, with the GWT version of the compiler.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=130951427

src/com/google/javascript/jscomp/ReplaceCssNames.java

@@ -81,7 +81,7 @@
  */
 class ReplaceCssNames implements CompilerPass {
 
-  static final String GET_CSS_NAME_FUNCTION = "goog.getCssName";
+  static final Node GET_CSS_NAME_FUNCTION = IR.getprop(IR.name("goog"), IR.string("getCssName"));
 
   static final DiagnosticType INVALID_NUM_ARGUMENTS_ERROR =
       DiagnosticType.error("JSC_GETCSSNAME_NUM_ARGS",
@@ -112,18 +112,25 @@ class ReplaceCssNames implements CompilerPass {
 
   private final Set<String> whitelist;
 
-  private final TypeI nativeStringType;
+  private TypeI nativeStringType;
 
   ReplaceCssNames(AbstractCompiler compiler,
       @Nullable Map<String, Integer> cssNames,
       @Nullable Set<String> whitelist) {
     this.compiler = compiler;
     this.cssNames = cssNames;
     this.whitelist = whitelist;
-    this.nativeStringType =
+  }
+
+  private TypeI getNativeStringType() {
+    if (nativeStringType == null) {
+      nativeStringType =
         compiler.getTypeIRegistry().getNativeType(STRING_TYPE);
+    }
+    return nativeStringType;
   }
 
+
   @Override
   public void process(Node externs, Node root) {
     // The CssRenamingMap may not have been available from the compiler when
@@ -180,7 +187,7 @@ public void visit(NodeTraversal t, Node n, Node parent) {
                   IR.string("-" + second.getString())
                       .useSourceInfoIfMissingFrom(second))
                   .useSourceInfoIfMissingFrom(n);
-              replacement.setTypeI(nativeStringType);
+              replacement.setTypeI(getNativeStringType());
               parent.replaceChild(n, replacement);
               compiler.reportCodeChange();
             }