Revert "Implement substitution for type variables."

sdk/lib/_internal/compiler/implementation/js_backend/namer.dart

Index: sdk/lib/_internal/compiler/implementation/js_backend/namer.dart
diff --git a/sdk/lib/_internal/compiler/implementation/js_backend/namer.dart b/sdk/lib/_internal/compiler/implementation/js_backend/namer.dart
index 63871e127417b64ed163e6473f47f83836ca7781..70f0c68cbb4ae8253740770c8cfb212e218b9b7b 100644
--- a/sdk/lib/_internal/compiler/implementation/js_backend/namer.dart
+++ b/sdk/lib/_internal/compiler/implementation/js_backend/namer.dart
@@ -670,8 +670,6 @@ class Namer implements ClosureNamer {
 
   String operatorIsPrefix() => r'$is';
 
-  String operatorAsPrefix() => r'$as';
-
   String operatorIs(Element element) {
     // TODO(erikcorry): Reduce from $isx to ix when we are minifying.
     return '${operatorIsPrefix()}${getName(element)}';
@@ -689,10 +687,6 @@ class Namer implements ClosureNamer {
     return name;
   }
 
-  String substitutionName(Element element) {
-    return '${operatorAsPrefix()}${getName(element)}';
-  }
-
   String safeName(String name) => _safeName(name, jsReserved);
   String safeVariableName(String name) => _safeName(name, jsVariableReserved);