VM: Add dart_precompiled build target, a standalone VM without the JIT compiler.

runtime/vm/precompiler.cc

Index: runtime/vm/precompiler.cc
diff --git a/runtime/vm/precompiler.cc b/runtime/vm/precompiler.cc
index c1bf705fe8fed0204a7d713793612f9cec60b8b7..78f8de2411f3d12c430bb9a6eb5a440d866ebe58 100644
--- a/runtime/vm/precompiler.cc
+++ b/runtime/vm/precompiler.cc
@@ -588,6 +588,7 @@ void Precompiler::AddInstantiatedClass(const Class& cls) {
 
   class_count_++;
   cls.set_is_allocated(true);
+  cls.EnsureIsFinalized(T);

[rmacnak, 2015/11/17 20:51:18]

All the classes should have been finalized before we get here.

[Florian Schneider, 2015/11/18 11:44:09]

Not true for certain signature classes: If you set a breakpoint in
EnsureFinalized when running a precompiled snapshot you'll see which ones.

There may be something missing in the tree-shaking code though.

[rmacnak, 2015/11/18 19:00:07]

Oh, right. Signature classes may be created as we parse functions.

   changed_ = true;
 
   if (FLAG_trace_precompiler) {