Fix bug from mappedBy -> map conversion.

sdk/lib/_internal/compiler/implementation/js/nodes.dart

Index: sdk/lib/_internal/compiler/implementation/js/nodes.dart
diff --git a/sdk/lib/_internal/compiler/implementation/js/nodes.dart b/sdk/lib/_internal/compiler/implementation/js/nodes.dart
index 148547e5076023b6ae6f05611a77d55b6c895b78..da8cd445101840db456220c271eda22617c5f724 100644
--- a/sdk/lib/_internal/compiler/implementation/js/nodes.dart
+++ b/sdk/lib/_internal/compiler/implementation/js/nodes.dart
@@ -778,7 +778,7 @@ class ArrayInitializer extends Expression {
 
   ArrayInitializer(this.length, this.elements);
 
-  factory ArrayInitializer.from(List<Expression> expressions) =>
+  factory ArrayInitializer.from(Iterable<Expression> expressions) =>
       new ArrayInitializer(expressions.length, _convert(expressions));
 
   accept(NodeVisitor visitor) => visitor.visitArrayInitializer(this);
@@ -789,7 +789,7 @@ class ArrayInitializer extends Expression {
 
   int get precedenceLevel => PRIMARY;
 
-  static List<ArrayElement> _convert(List<Expression> expressions) {
+  static List<ArrayElement> _convert(Iterable<Expression> expressions) {
     int index = 0;
     return expressions.map(
         (expression) => new ArrayElement(index++, expression))