Implement 'dart:typeddata' directly in the VM instead of using 'dart:scalarlist'

runtime/vm/object_store.h

Index: runtime/vm/object_store.h
===================================================================
--- runtime/vm/object_store.h	(revision 19652)
+++ runtime/vm/object_store.h	(working copy)
@@ -351,6 +351,13 @@
     external_float64_array_class_ = value.raw();
   }
 
+  RawArray* typeddata_classes() const {
+    return typeddata_classes_;
+  }
+  void set_typeddata_classes(const Array& value) {
+    typeddata_classes_ = value.raw();
+  }
+
   RawClass* stacktrace_class() const {
     return stacktrace_class_;
   }
@@ -642,6 +649,7 @@
   RawClass* external_float32x4_array_class_;
   RawClass* external_float32_array_class_;
   RawClass* external_float64_array_class_;
+  RawArray* typeddata_classes_;
   RawClass* stacktrace_class_;
   RawClass* jsregexp_class_;
   RawClass* weak_property_class_;