More dart2js strong mode cleanup.

pkg/compiler/lib/src/elements/elements.dart

Index: pkg/compiler/lib/src/elements/elements.dart
diff --git a/pkg/compiler/lib/src/elements/elements.dart b/pkg/compiler/lib/src/elements/elements.dart
index c0c3834d3cae22d5d6ed75f0a5092a8cef3c656e..c10d56c3f2b785f4314a4470290a0cca7ad5b21d 100644
--- a/pkg/compiler/lib/src/elements/elements.dart
+++ b/pkg/compiler/lib/src/elements/elements.dart
@@ -746,13 +746,14 @@ class Elements {
     List<T> result = <T>[];
 
     FunctionSignature parameters = element.functionSignature;
-    parameters.forEachRequiredParameter((ParameterElement element) {
+    parameters.forEachRequiredParameter((_) {
       result.add(compileArgument(arguments.head));
       arguments = arguments.tail;
     });
 
     if (!parameters.optionalParametersAreNamed) {
-      parameters.forEachOptionalParameter((ParameterElement element) {
+      parameters.forEachOptionalParameter((_element) {
+        ParameterElement element = _element;
         if (!arguments.isEmpty) {
           result.add(compileArgument(arguments.head));
           arguments = arguments.tail;
@@ -770,7 +771,8 @@ class Elements {
       // Iterate over the optional parameters of the signature, and try to
       // find them in [compiledNamedArguments]. If found, we use the
       // value in the temporary list, otherwise the default value.
-      parameters.orderedOptionalParameters.forEach((ParameterElement element) {
+      parameters.orderedOptionalParameters.forEach((_element) {
+        ParameterElement element = _element;
         int foundIndex = callStructure.namedArguments.indexOf(element.name);
         if (foundIndex != -1) {
           result.add(compiledNamedArguments[foundIndex]);
@@ -815,18 +817,21 @@ class Elements {
     // that we can call [addArgumentsToList].
     Link<Node> computeCallNodesFromParameters() {
       LinkBuilder<Node> builder = new LinkBuilder<Node>();
-      signature.forEachRequiredParameter((ParameterElement element) {
+      signature.forEachRequiredParameter((_element) {
+        ParameterElement element = _element;
         Node node = element.node;
         mapping[node] = element;
         builder.addLast(node);
       });
       if (signature.optionalParametersAreNamed) {
-        signature.forEachOptionalParameter((ParameterElement element) {
+        signature.forEachOptionalParameter((_element) {
+          ParameterElement element = _element;
           mapping[element.initializer] = element;
           builder.addLast(new NamedArgument(null, null, element.initializer));
         });
       } else {
-        signature.forEachOptionalParameter((ParameterElement element) {
+        signature.forEachOptionalParameter((_element) {
+          ParameterElement element = _element;
           Node node = element.node;
           mapping[node] = element;
           builder.addLast(node);