Avoid repeated declaration of the same loop variable.

lib/compiler/implementation/ssa/codegen.dart

Index: lib/compiler/implementation/ssa/codegen.dart
diff --git a/lib/compiler/implementation/ssa/codegen.dart b/lib/compiler/implementation/ssa/codegen.dart
index 44664d94087df2d54bcf4b0b3f45170daf482f32..6465ac096f6201d9ddddbf7a6968bcd97371e406 100644
--- a/lib/compiler/implementation/ssa/codegen.dart
+++ b/lib/compiler/implementation/ssa/codegen.dart
@@ -468,9 +468,12 @@ class SsaCodeGenerator implements HVisitor, HBlockInformationVisitor {
           declaredVariables.add(variableName);
           buffer.add("var ");
         }
-      } else if (!isGeneratingDeclaration()
-                 && !isVariableDeclared(variableName)) {
-        delayedVariablesDeclaration.add(variableName);
+      } else if (!isVariableDeclared(variableName)) {
+        if (!isGeneratingDeclaration()) {
+          delayedVariablesDeclaration.add(variableName);
+        } else {
+          declaredVariables.add(variableName);
+        }
       }
     } else if (!isVariableDeclared(variableName)) {
       declaredVariables.add(variableName);