Reapply "Change the SSA construction pass to also construct def-use chains."

Reapply "Change the SSA construction pass to also construct def-use chains."

This reapplies svn commit 18813 with a bug fix.  In the case of an
inlined call whose value is not used, the inliner hase inserted a use
of the return value's definition, which must be removed.

R=vegorov@google.com
BUG=

Committed: https://code.google.com/p/dart/source/detail?r=18827

[Kevin Millikin (Google), 2013-02-21 11:48:35]

The diff from the previous change is:

--- a/runtime/vm/flow_graph_builder.cc
+++ b/runtime/vm/flow_graph_builder.cc
@@ -211,6 +211,12 @@ void ValueInliningContext::ReplaceCall(FlowGraph*
caller_graph,
       }
       // Replace uses of the call with the phi.
       call->ReplaceUsesWith(phi);
+    } else {
+      // In the case that the result is unused, remove the return value uses
+      // from their definition's use list.
+      for (intptr_t i = 0; i < num_exits; ++i) {
+        ValueAt(i)->RemoveFromUseList();
+      }
     }
     // Remove the call from the graph.
     call->previous()->LinkTo(callee_entry->next());

[Vyacheslav Egorov (Google), 2013-02-21 11:52:34]

lgtm

[Kevin Millikin (Google), 2013-02-21 12:57:52]

Committed patchset #1 manually as r18827 (presubmit successful).