Pass handles not raw objects into methods.

runtime/vm/dart_entry.cc

Index: runtime/vm/dart_entry.cc
===================================================================
--- runtime/vm/dart_entry.cc	(revision 15741)
+++ runtime/vm/dart_entry.cc	(working copy)
@@ -119,8 +119,8 @@
 }
 
 
-ArgumentsDescriptor::ArgumentsDescriptor(RawObject* array)
-    : array_(Array::CheckedHandle(array)) {
+ArgumentsDescriptor::ArgumentsDescriptor(const Array& array)
+    : array_(array) {
 }
 
 
@@ -134,10 +134,12 @@
 }
 
 
-RawObject* ArgumentsDescriptor::NameAt(intptr_t index) const {
-  return array_.At(kFirstNamedEntryIndex +
-                   (index * kNamedEntrySize) +
-                   kNameOffset);
+RawString* ArgumentsDescriptor::NameAt(intptr_t index) const {
+  String& result = String::Handle();

[Florian Schneider, 2012/12/06 09:48:16]

Allocating a handle just for casting seems an expensive way to cast to String.
Why not not return RawObject* as before? The caller will almost always allocate
a handle itself and can do the cast as well.

[Kevin Millikin (Google), 2012/12/06 10:44:02]

The only caller just does pointer equality to RawString*, which works if this is
RawObject*.  In fact, this method can be replaced by:

bool ArgumentsDescriptor::MatchNameAt(intptr_t index,
                                      const String& other) const {
  return (array_.At(...) == other.raw());
}

+  result ^= array_.At(kFirstNamedEntryIndex +
+                      (index * kNamedEntrySize) +
+                      kNameOffset);
+  return result.raw();
 }