Remove unused code

pkg/compiler/lib/src/js_backend/codegen/codegen.dart

Index: pkg/compiler/lib/src/js_backend/codegen/codegen.dart
diff --git a/pkg/compiler/lib/src/js_backend/codegen/codegen.dart b/pkg/compiler/lib/src/js_backend/codegen/codegen.dart
index 9dbaad40aa98b688eb834730d87bc21b3207a19c..84d92ef2c75ce795101e0832e4cb64a160d857dd 100644
--- a/pkg/compiler/lib/src/js_backend/codegen/codegen.dart
+++ b/pkg/compiler/lib/src/js_backend/codegen/codegen.dart
@@ -218,7 +218,6 @@ class CodeGenerator extends tree_ir.Visitor<dynamic, js.Expression> {
   @override
   js.Expression visitVariable(tree_ir.Variable node) {
     return new js.VariableUse(getVariableName(node));
-    // TODO: implement visitVariable
   }
 
   @override
@@ -254,10 +253,6 @@ class CodeGenerator extends tree_ir.Visitor<dynamic, js.Expression> {
 
   @override
   void visitAssign(tree_ir.Assign node) {
-
-    bool isFirstOccurrence = (variableNames[node.variable] == null);
-    bool isDeclaredHere = node.variable.host.element == currentFunction;
-    String name = getVariableName(node.variable);
     tree_ir.Expression value = node.definition;
     js.Expression definition = visitExpression(value);