Change NotImplementedException to UnimplementedError.

lib/html/dartium/html_dartium.dart

Index: lib/html/dartium/html_dartium.dart
diff --git a/lib/html/dartium/html_dartium.dart b/lib/html/dartium/html_dartium.dart
index 6d35628cc1313668a58e5db8a989f68050bd263f..45b33ca0bcb19ab6f726d9439ef391ad476349ed 100644
--- a/lib/html/dartium/html_dartium.dart
+++ b/lib/html/dartium/html_dartium.dart
@@ -11505,7 +11505,7 @@ class _FilteredElementList implements List {
   }
 
   void setRange(int start, int rangeLength, List from, [int startFrom = 0]) {
-    throw const NotImplementedException();
+    throw new UnimplementedError();
   }
 
   void removeRange(int start, int rangeLength) {
@@ -11513,7 +11513,7 @@ class _FilteredElementList implements List {
   }
 
   void insertRange(int start, int rangeLength, [initialValue = null]) {
-    throw const NotImplementedException();
+    throw new UnimplementedError();
   }
 
   void clear() {
@@ -12721,15 +12721,15 @@ class _ChildrenElementList implements List {
   }
 
   void setRange(int start, int rangeLength, List from, [int startFrom = 0]) {
-    throw const NotImplementedException();
+    throw new UnimplementedError();
   }
 
   void removeRange(int start, int rangeLength) {
-    throw const NotImplementedException();
+    throw new UnimplementedError();
   }
 
   void insertRange(int start, int rangeLength, [initialValue = null]) {
-    throw const NotImplementedException();
+    throw new UnimplementedError();
   }
 
   List getRange(int start, int rangeLength) =>
@@ -44283,7 +44283,7 @@ class _Utils {
 
   static Map createMap() => {};
 
-  static makeNotImplementedException(String fileName, int lineNo) {
+  static makeUnimplementedError(String fileName, int lineNo) {
     return new UnsupportedError('[info: $fileName:$lineNo]');
   }