Make mappedBy lazy.

sdk/lib/svg/dart2js/svg_dart2js.dart

Index: sdk/lib/svg/dart2js/svg_dart2js.dart
diff --git a/sdk/lib/svg/dart2js/svg_dart2js.dart b/sdk/lib/svg/dart2js/svg_dart2js.dart
index 125a310f2df29cc301b9da8e05579acda76b2b5e..df32cb3bf8da6f357c0d740e830149fa4bd0b6d0 100644
--- a/sdk/lib/svg/dart2js/svg_dart2js.dart
+++ b/sdk/lib/svg/dart2js/svg_dart2js.dart
@@ -349,7 +349,7 @@ class SVGAnimatedLengthList implements JavaScriptIndexingBehavior, List<SVGAnima
 
   void forEach(void f(SVGAnimatedLength element)) => _Collections.forEach(this, f);
 
-  Collection mappedBy(f(SVGAnimatedLength element)) => _Collections.mappedBy(this, [], f);
+  Iterable mappedBy(f(SVGAnimatedLength element)) => new MappedIterable(this, f);
 
   Collection<SVGAnimatedLength> where(bool f(SVGAnimatedLength element)) =>
      _Collections.where(this, <SVGAnimatedLength>[], f);
@@ -460,7 +460,7 @@ class SVGAnimatedNumberList implements JavaScriptIndexingBehavior, List<SVGAnima
 
   void forEach(void f(SVGAnimatedNumber element)) => _Collections.forEach(this, f);
 
-  Collection mappedBy(f(SVGAnimatedNumber element)) => _Collections.mappedBy(this, [], f);
+  Iterable mappedBy(f(SVGAnimatedNumber element)) => new MappedIterable(this, f);
 
   Collection<SVGAnimatedNumber> where(bool f(SVGAnimatedNumber element)) =>
      _Collections.where(this, <SVGAnimatedNumber>[], f);
@@ -599,7 +599,7 @@ class SVGAnimatedTransformList implements JavaScriptIndexingBehavior, List<SVGAn
 
   void forEach(void f(SVGAnimateTransformElement element)) => _Collections.forEach(this, f);
 
-  Collection mappedBy(f(SVGAnimateTransformElement element)) => _Collections.mappedBy(this, [], f);
+  Iterable mappedBy(f(SVGAnimateTransformElement element)) => new MappedIterable(this, f);
 
   Collection<SVGAnimateTransformElement> where(bool f(SVGAnimateTransformElement element)) =>
      _Collections.where(this, <SVGAnimateTransformElement>[], f);
@@ -3020,7 +3020,7 @@ class SVGLengthList implements JavaScriptIndexingBehavior, List<SVGLength> nativ
 
   void forEach(void f(SVGLength element)) => _Collections.forEach(this, f);
 
-  Collection mappedBy(f(SVGLength element)) => _Collections.mappedBy(this, [], f);
+  Iterable mappedBy(f(SVGLength element)) => new MappedIterable(this, f);
 
   Collection<SVGLength> where(bool f(SVGLength element)) =>
      _Collections.where(this, <SVGLength>[], f);
@@ -3509,7 +3509,7 @@ class SVGNumberList implements JavaScriptIndexingBehavior, List<SVGNumber> nativ
 
   void forEach(void f(SVGNumber element)) => _Collections.forEach(this, f);
 
-  Collection mappedBy(f(SVGNumber element)) => _Collections.mappedBy(this, [], f);
+  Iterable mappedBy(f(SVGNumber element)) => new MappedIterable(this, f);
 
   Collection<SVGNumber> where(bool f(SVGNumber element)) =>
      _Collections.where(this, <SVGNumber>[], f);
@@ -4168,7 +4168,7 @@ class SVGPathSegList implements JavaScriptIndexingBehavior, List<SVGPathSeg> nat
 
   void forEach(void f(SVGPathSeg element)) => _Collections.forEach(this, f);
 
-  Collection mappedBy(f(SVGPathSeg element)) => _Collections.mappedBy(this, [], f);
+  Iterable mappedBy(f(SVGPathSeg element)) => new MappedIterable(this, f);
 
   Collection<SVGPathSeg> where(bool f(SVGPathSeg element)) =>
      _Collections.where(this, <SVGPathSeg>[], f);
@@ -5037,7 +5037,7 @@ class SVGStringList implements JavaScriptIndexingBehavior, List<String> native "
 
   void forEach(void f(String element)) => _Collections.forEach(this, f);
 
-  Collection mappedBy(f(String element)) => _Collections.mappedBy(this, [], f);
+  Iterable mappedBy(f(String element)) => new MappedIterable(this, f);
 
   Collection<String> where(bool f(String element)) =>
      _Collections.where(this, <String>[], f);
@@ -5601,7 +5601,7 @@ class SVGTransformList implements JavaScriptIndexingBehavior, List<SVGTransform>
 
   void forEach(void f(SVGTransform element)) => _Collections.forEach(this, f);
 
-  Collection mappedBy(f(SVGTransform element)) => _Collections.mappedBy(this, [], f);
+  Iterable mappedBy(f(SVGTransform element)) => new MappedIterable(this, f);
 
   Collection<SVGTransform> where(bool f(SVGTransform element)) =>
      _Collections.where(this, <SVGTransform>[], f);
@@ -5979,7 +5979,7 @@ class _SVGElementInstanceList implements JavaScriptIndexingBehavior, List<SVGEle
 
   void forEach(void f(SVGElementInstance element)) => _Collections.forEach(this, f);
 
-  Collection mappedBy(f(SVGElementInstance element)) => _Collections.mappedBy(this, [], f);
+  Iterable mappedBy(f(SVGElementInstance element)) => new MappedIterable(this, f);
 
   Collection<SVGElementInstance> where(bool f(SVGElementInstance element)) =>
      _Collections.where(this, <SVGElementInstance>[], f);