More dart2js strong mode cleanup.

pkg/compiler/lib/src/kernel/kernel_visitor.dart

Index: pkg/compiler/lib/src/kernel/kernel_visitor.dart
diff --git a/pkg/compiler/lib/src/kernel/kernel_visitor.dart b/pkg/compiler/lib/src/kernel/kernel_visitor.dart
index a344f420a5bb35dc7fa9097c46e79d68449fb067..97055ecdba01e98324d032e2400ccf6cf967b388 100644
--- a/pkg/compiler/lib/src/kernel/kernel_visitor.dart
+++ b/pkg/compiler/lib/src/kernel/kernel_visitor.dart
@@ -1493,7 +1493,8 @@ class KernelVisitor extends Object
         // Mixin application implicit super call.
         arguments = <ir.Expression>[];
         named = <ir.NamedExpression>[];
-        signature.orderedForEachParameter((ParameterElement parameter) {
+        signature.orderedForEachParameter((_parameter) {
+          ParameterElement parameter = _parameter;
           ir.VariableGet argument = buildLocalGet(parameter);
           if (parameter.isNamed) {
             named.add(new ir.NamedExpression(parameter.name, argument));
@@ -2112,7 +2113,8 @@ class KernelVisitor extends Object
     if (function.hasFunctionSignature) {
       FunctionSignature signature = function.functionSignature;
       requiredParameterCount = signature.requiredParameterCount;
-      signature.forEachParameter((ParameterElement parameter) {
+      signature.forEachParameter((_parameter) {
+        ParameterElement parameter = _parameter;
         ir.VariableDeclaration variable = getLocal(parameter);
         if (parameter.isNamed) {
           namedParameters.add(variable);
@@ -2120,7 +2122,8 @@ class KernelVisitor extends Object
           positionalParameters.add(variable);
         }
       });
-      signature.forEachParameter((ParameterElement parameter) {
+      signature.forEachParameter((_parameter) {
+        ParameterElement parameter = _parameter;
         if (!parameter.isOptional) return;
         ir.Expression initializer = visitForValue(parameter.initializer);
         ir.VariableDeclaration variable = getLocal(parameter);
@@ -2878,6 +2881,7 @@ class KernelVisitor extends Object
   }
 
   @override
+  // TODO(ahe): Remove this ignore when strong-mode only.
   // ignore: INVALID_METHOD_OVERRIDE_RETURN_TYPE
   ir.Node visitVariableDefinitions(VariableDefinitions definitions) {
     // TODO(ahe): This method is copied from [SemanticDeclarationResolvedMixin]
@@ -2886,12 +2890,11 @@ class KernelVisitor extends Object
     computeVariableStructures(definitions,
         (Node node, VariableStructure structure) {
       if (structure == null) {
-        return internalError(node, 'No structure for $node');
+        internalError(node, 'No structure for $node');
       } else {
         ir.VariableDeclaration variable =
             structure.dispatch(declVisitor, node, null);
         variables.add(variable);
-        return variable;
       }
     });
     if (variables.length == 1) return variables.single;