allow JS builtin to be typed as needed

lib/runtime/dart/_native_typed_data.js

Index: lib/runtime/dart/_native_typed_data.js
diff --git a/lib/runtime/dart/_native_typed_data.js b/lib/runtime/dart/_native_typed_data.js
index bac1b0086328281b16e1c5c010b281c229f50fbf..9de70681503d82e51f517633e7f880d80f836130 100644
--- a/lib/runtime/dart/_native_typed_data.js
+++ b/lib/runtime/dart/_native_typed_data.js
@@ -583,13 +583,13 @@ dart_library.library('dart/_native_typed_data', null, /* Imports */[
       dart.throw(new core.UnsupportedError('Uint64 accessor not supported by dart2js.'));
     }
     static _create1(arg) {
-      return dart.as(new DataView(new ArrayBuffer(arg)), NativeByteData);
+      return new DataView(new ArrayBuffer(arg));
     }
     static _create2(arg1, arg2) {
-      return dart.as(new DataView(arg1, arg2), NativeByteData);
+      return new DataView(arg1, arg2);
     }
     static _create3(arg1, arg2, arg3) {
-      return dart.as(new DataView(arg1, arg2, arg3), NativeByteData);
+      return new DataView(arg1, arg2, arg3);
     }
   }
   NativeByteData[dart.implements] = () => [typed_data.ByteData];
@@ -654,7 +654,7 @@ dart_library.library('dart/_native_typed_data', null, /* Imports */[
         dart.throw(new core.StateError('Not enough elements'));
       }
       if (skipCount != 0 || sourceLength != count) {
-        source = dart.as(source.subarray(skipCount, dart.notNull(skipCount) + dart.notNull(count)), NativeTypedArray);
+        source = source.subarray(skipCount, dart.notNull(skipCount) + dart.notNull(count));
       }
       this.set(source, start);
     }
@@ -740,13 +740,13 @@ dart_library.library('dart/_native_typed_data', null, /* Imports */[
       return NativeFloat32List._create1(source);
     }
     static _create1(arg) {
-      return dart.as(new Float32Array(arg), NativeFloat32List);
+      return new Float32Array(arg);
     }
     static _create2(arg1, arg2) {
-      return dart.as(new Float32Array(arg1, arg2), NativeFloat32List);
+      return new Float32Array(arg1, arg2);
     }
     static _create3(arg1, arg2, arg3) {
-      return dart.as(new Float32Array(arg1, arg2, arg3), NativeFloat32List);
+      return new Float32Array(arg1, arg2, arg3);
     }
   }
   NativeFloat32List[dart.implements] = () => [typed_data.Float32List];
@@ -787,13 +787,13 @@ dart_library.library('dart/_native_typed_data', null, /* Imports */[
       return NativeFloat64List._create1(source);
     }
     static _create1(arg) {
-      return dart.as(new Float64Array(arg), NativeFloat64List);
+      return new Float64Array(arg);
     }
     static _create2(arg1, arg2) {
-      return dart.as(new Float64Array(arg1, arg2), NativeFloat64List);
+      return new Float64Array(arg1, arg2);
     }
     static _create3(arg1, arg2, arg3) {
-      return dart.as(new Float64Array(arg1, arg2, arg3), NativeFloat64List);
+      return new Float64Array(arg1, arg2, arg3);
     }
   }
   NativeFloat64List[dart.implements] = () => [typed_data.Float64List];
@@ -838,13 +838,13 @@ dart_library.library('dart/_native_typed_data', null, /* Imports */[
       return NativeInt16List._create1(source);
     }
     static _create1(arg) {
-      return dart.as(new Int16Array(arg), NativeInt16List);
+      return new Int16Array(arg);
     }
     static _create2(arg1, arg2) {
-      return dart.as(new Int16Array(arg1, arg2), NativeInt16List);
+      return new Int16Array(arg1, arg2);
     }
     static _create3(arg1, arg2, arg3) {
-      return dart.as(new Int16Array(arg1, arg2, arg3), NativeInt16List);
+      return new Int16Array(arg1, arg2, arg3);
     }
   }
   NativeInt16List[dart.implements] = () => [typed_data.Int16List];
@@ -892,13 +892,13 @@ dart_library.library('dart/_native_typed_data', null, /* Imports */[
       return NativeInt32List._create1(source);
     }
     static _create1(arg) {
-      return dart.as(new Int32Array(arg), NativeInt32List);
+      return new Int32Array(arg);
     }
     static _create2(arg1, arg2) {
-      return dart.as(new Int32Array(arg1, arg2), NativeInt32List);
+      return new Int32Array(arg1, arg2);
     }
     static _create3(arg1, arg2, arg3) {
-      return dart.as(new Int32Array(arg1, arg2, arg3), NativeInt32List);
+      return new Int32Array(arg1, arg2, arg3);
     }
   }
   NativeInt32List[dart.implements] = () => [typed_data.Int32List];
@@ -946,13 +946,13 @@ dart_library.library('dart/_native_typed_data', null, /* Imports */[
       return NativeInt8List._create1(source);
     }
     static _create1(arg) {
-      return dart.as(new Int8Array(arg), NativeInt8List);
+      return new Int8Array(arg);
     }
     static _create2(arg1, arg2) {
-      return dart.as(new Int8Array(arg1, arg2), NativeInt8List);
+      return new Int8Array(arg1, arg2);
     }
     static _create3(arg1, arg2, arg3) {
-      return dart.as(new Int8Array(arg1, arg2, arg3), typed_data.Int8List);
+      return new Int8Array(arg1, arg2, arg3);
     }
   }
   NativeInt8List[dart.implements] = () => [typed_data.Int8List];
@@ -1000,13 +1000,13 @@ dart_library.library('dart/_native_typed_data', null, /* Imports */[
       return NativeUint16List._create1(source);
     }
     static _create1(arg) {
-      return dart.as(new Uint16Array(arg), NativeUint16List);
+      return new Uint16Array(arg);
     }
     static _create2(arg1, arg2) {
-      return dart.as(new Uint16Array(arg1, arg2), NativeUint16List);
+      return new Uint16Array(arg1, arg2);
     }
     static _create3(arg1, arg2, arg3) {
-      return dart.as(new Uint16Array(arg1, arg2, arg3), NativeUint16List);
+      return new Uint16Array(arg1, arg2, arg3);
     }
   }
   NativeUint16List[dart.implements] = () => [typed_data.Uint16List];
@@ -1054,13 +1054,13 @@ dart_library.library('dart/_native_typed_data', null, /* Imports */[
       return NativeUint32List._create1(source);
     }
     static _create1(arg) {
-      return dart.as(new Uint32Array(arg), NativeUint32List);
+      return new Uint32Array(arg);
     }
     static _create2(arg1, arg2) {
-      return dart.as(new Uint32Array(arg1, arg2), NativeUint32List);
+      return new Uint32Array(arg1, arg2);
     }
     static _create3(arg1, arg2, arg3) {
-      return dart.as(new Uint32Array(arg1, arg2, arg3), NativeUint32List);
+      return new Uint32Array(arg1, arg2, arg3);
     }
   }
   NativeUint32List[dart.implements] = () => [typed_data.Uint32List];
@@ -1111,13 +1111,13 @@ dart_library.library('dart/_native_typed_data', null, /* Imports */[
       return NativeUint8ClampedList._create1(source);
     }
     static _create1(arg) {
-      return dart.as(new Uint8ClampedArray(arg), NativeUint8ClampedList);
+      return new Uint8ClampedArray(arg);
     }
     static _create2(arg1, arg2) {
-      return dart.as(new Uint8ClampedArray(arg1, arg2), NativeUint8ClampedList);
+      return new Uint8ClampedArray(arg1, arg2);
     }
     static _create3(arg1, arg2, arg3) {
-      return dart.as(new Uint8ClampedArray(arg1, arg2, arg3), NativeUint8ClampedList);
+      return new Uint8ClampedArray(arg1, arg2, arg3);
     }
   }
   NativeUint8ClampedList[dart.implements] = () => [typed_data.Uint8ClampedList];
@@ -1168,13 +1168,13 @@ dart_library.library('dart/_native_typed_data', null, /* Imports */[
       return NativeUint8List._create1(source);
     }
     static _create1(arg) {
-      return dart.as(new Uint8Array(arg), NativeUint8List);
+      return new Uint8Array(arg);
     }
     static _create2(arg1, arg2) {
-      return dart.as(new Uint8Array(arg1, arg2), NativeUint8List);
+      return new Uint8Array(arg1, arg2);
     }
     static _create3(arg1, arg2, arg3) {
-      return dart.as(new Uint8Array(arg1, arg2, arg3), NativeUint8List);
+      return new Uint8Array(arg1, arg2, arg3);
     }
   }
   NativeUint8List[dart.implements] = () => [typed_data.Uint8List];