Move recording of definition used from the value to the definition.

Move recording of definition uses from the value to the definition.

It was weird that this method mutated an object that wasn't even
mentioned in the call.  Also, change Definition::ReplaceUsesWith so that
it appends all at once instead of consing each individual use.

Committed: https://code.google.com/p/dart/source/detail?r=18048

[Kevin Millikin (Google), 2013-01-31 16:37:13]

https://codereview.chromium.org/12091091/diff/1/runtime/vm/intermediate_langu...
File runtime/vm/intermediate_language.cc (right):

https://codereview.chromium.org/12091091/diff/1/runtime/vm/intermediate_langu...
runtime/vm/intermediate_language.cc:1726:
null_constant->AddInputUse(instantiator_type_arguments());
These three lines are going to get combined somehow soon.

[Kevin Millikin (Google), 2013-02-01 09:33:18]

As discussed offline, I restored the remove function to class Value.  I made it
more general: the same function will remove the use from whichever use list it
happens to be in.

[Kevin Millikin (Google), 2013-02-01 09:35:24]

https://codereview.chromium.org/12091091/diff/1005/runtime/vm/intermediate_la...
File runtime/vm/intermediate_language.cc (right):

https://codereview.chromium.org/12091091/diff/1005/runtime/vm/intermediate_la...
runtime/vm/intermediate_language.cc:649: prev->set_next_use(next);
Here we still assume use lists are coherent.  If this use is the head of the use
list for some other definition, prev will be NULL.

[Vyacheslav Egorov (Google), 2013-02-01 14:38:19]

lgtm

https://codereview.chromium.org/12091091/diff/1005/runtime/vm/intermediate_la...
File runtime/vm/intermediate_language.cc (right):

https://codereview.chromium.org/12091091/diff/1005/runtime/vm/intermediate_la...
runtime/vm/intermediate_language.cc:691: current->set_next_use(next);
There is a bit of duplicated code here with above one. Consider making a
function.