Add a new operator |= which does a simple assignment of the raw pointer into

Add a new operator |= which does a simple assignment of the raw pointer into
a handle without any vtable settings. In debug mode there are the usual checks
to ensure that the vtable in the handle matches the expected vtable value
based on the dynamic type of the object.

It is useful in loopy code as follows:
  const Array& funcs = class.functions();
  Function func = Function::Handle();
  for (int i = 0; i < 100000000; i++) {
    func |= funcs.At(i);
  }
Committed: https://code.google.com/p/dart/source/detail?r=17244

[Ivan Posva, 2013-01-17 23:24:23]

LGTMwC -ip

https://chromiumcodereview.appspot.com/11979003/diff/4001/runtime/vm/object.cc
File runtime/vm/object.cc (right):

https://chromiumcodereview.appspot.com/11979003/diff/4001/runtime/vm/object.c...
runtime/vm/object.cc:1210:
isolate->class_table()->At(cid)->ptr()->handle_vtable_);
Do we really need to check this one-time assertion for every handle assignment?

[siva, 2013-01-18 00:08:38]

https://chromiumcodereview.appspot.com/11979003/diff/4001/runtime/vm/object.cc
File runtime/vm/object.cc (right):

https://chromiumcodereview.appspot.com/11979003/diff/4001/runtime/vm/object.c...
runtime/vm/object.cc:1210:
isolate->class_table()->At(cid)->ptr()->handle_vtable_);
True, this assertion can be pulled out into a one time assertion which is done
in dart::InitializeIsolate().

Will make this change in another CL.

On 2013/01/17 23:24:23, Ivan Posva wrote:
> Do we really need to check this one-time assertion for every handle
assignment?