Teach Scopes whether they will end up being lazily compiled or not

src/compiler.cc

Index: src/compiler.cc
diff --git a/src/compiler.cc b/src/compiler.cc
index ec402fa82209339f2bddfcee9066b7e17ef90763..2673fee1a1d19e5c20978761cbbd84ddb8c2c612 100644
--- a/src/compiler.cc
+++ b/src/compiler.cc
@@ -1431,6 +1431,7 @@ bool Compiler::EnsureDeoptimizationSupport(CompilationInfo* info) {
     RecordFunctionCompilation(CodeEventListener::LAZY_COMPILE_TAG,
                               &unoptimized);
   }
+  info->parse_info()->set_will_serialize(false);

[marja, 2016/10/06 11:53:06]

Why is this needed, shouldn't there be a default that we're not going to
serialize?

[jochen (gone - plz use gerrit), 2016/10/06 15:05:04]

In EnsureDeoptimizationSupport we might recompile the unoptimized code. For
this, we might have to enable the serializer.

The CompilationInfo "unoptimized", however, uses the same ParseInfo as the
optimized job will use, so I have to reset that flag now that it lives on
ParseInfo and no longer on CompilationInfo.

[marja, 2016/10/07 08:25:59]

Offline discussion: this code for resetting the flag is actually conceptually
close to the place where the flag will potentially be set, but it's hard to see
since the setting is potentially done in EnableDeoptimizationSupport.

Maybe add a comment?

   return true;
 }
 
@@ -1794,6 +1795,8 @@ Handle<SharedFunctionInfo> Compiler::GetSharedFunctionInfo(
   lazy &=
       !(FLAG_ignition && FLAG_ignition_eager && !isolate->serializer_enabled());
 
+  DCHECK_EQ(lazy, literal->scope()->should_compile_lazily());
+
   // Generate code
   TimerEventScope<TimerEventCompileCode> timer(isolate);
   RuntimeCallTimerScope runtimeTimer(isolate, &RuntimeCallStats::CompileCode);