Support for dart:typed_data

tool/input_sdk/private/classes.dart

Index: tool/input_sdk/private/classes.dart
diff --git a/tool/input_sdk/private/classes.dart b/tool/input_sdk/private/classes.dart
index 7a784a4257c321f8ed92d193a05ddaca7ac5034c..fea07196580d0d4d389a7cea7a64bd59d070affc 100644
--- a/tool/input_sdk/private/classes.dart
+++ b/tool/input_sdk/private/classes.dart
@@ -259,6 +259,8 @@ defineNamedConstructor(clazz, name) => JS('', '''(() => {
 
 final _extensionType = JS('', 'Symbol("extensionType")');
 
+getExtensionType(obj) => JS('', '$obj[$_extensionType]');
+
 final dartx = JS('', '{}');
 
 getExtensionSymbol(name) => JS('', '''(() => {
@@ -269,6 +271,15 @@ getExtensionSymbol(name) => JS('', '''(() => {
 
 defineExtensionNames(names) => JS('', '$names.forEach($getExtensionSymbol)');
 
+// Install properties in prototype order.  Properties / descriptors from
+// more specific types should overwrite ones from less specific types.
+_installProperties(jsProto, extProto) => JS('', '''(() => {
+  if (extProto !== $Object.prototype && extProto !== jsProto) {
+    $_installProperties(jsProto, extProto.__proto__);
+  }
+  $copyTheseProperties(jsProto, extProto, $getOwnPropertySymbols(extProto));
+})()''');
+
 ///
 /// Copy symbols from the prototype of the source to destination.
 /// These are the only properties safe to copy onto an existing public
@@ -280,13 +291,8 @@ registerExtension(jsType, dartExtType) => JS('', '''(() => {
 
   // Mark the JS type's instances so we can easily check for extensions.
   $assert_(jsProto[$_extensionType] === void 0);
-  jsProto[$_extensionType] = extProto;
-
-  let dartObjProto = $Object.prototype;
-  while (extProto !== dartObjProto && extProto !== jsProto) {
-    $copyTheseProperties(jsProto, extProto, $getOwnPropertySymbols(extProto));
-    extProto = extProto.__proto__;
-  }
+  jsProto[$_extensionType] = $dartExtType;
+  $_installProperties(jsProto, extProto);
   let originalSigFn = $getOwnPropertyDescriptor($dartExtType, $_methodSig).get;
   $assert_(originalSigFn);
   $defineMemoizedGetter($jsType, $_methodSig, originalSigFn);
@@ -345,6 +351,9 @@ canonicalMember(obj, name) => JS('', '''(() => {
 /// Sets the type of `obj` to be `type`
 setType(obj, type) => JS('', '''(() => {
   $obj.__proto__ = $type.prototype;
+  // TODO(vsm): This should be set in registerExtension, but that is only
+  // invoked on the generic type (e.g., JSArray<dynamic>, not JSArray<int>).

[Jennifer Messerly, 2016/02/10 00:20:30]

Given a generic type T, it's possible to get its raw type R, then from that you
can get its extension type. This is all handled by dart.generic

So it shouldn't be necessary to put this here. We can already find the type for
List<int> and such, AFAIK. I'll add some code that should work on the other end.

[vsm, 2016/02/11 22:36:06]

I need this to go the other way around - i.e., to map the raw object back to the
generic type.

[Jennifer Messerly, 2016/02/11 23:04:57]

I'm 99% sure this should not be needed. In JavaScript:

    obj.__proto__.contstructor == type

so you don't need the _extensionType field. That's what I'm saying.
 

+  $obj.__proto__[$_extensionType] = type;

[Jennifer Messerly, 2016/02/10 00:20:30]

(possibly moot based on above comment)

I think this should be $type in the quasiquote scheme. (Whether this makes any
difference, I'm not sure. We really need to change the way the SDK libs are
written... it's kind of in an awkward place now)

[vsm, 2016/02/11 22:36:06]

Done.

   return $obj;
 })()''');