First version of the new generators implementation.

src/compiler.cc

Index: src/compiler.cc
diff --git a/src/compiler.cc b/src/compiler.cc
index 98d36748b59dbe87ace552bd69fd7faf96a68772..9d5bf20dfaa0a30e7972c3f5b79a7d2193a55cbb 100644
--- a/src/compiler.cc
+++ b/src/compiler.cc
@@ -315,6 +315,12 @@ OptimizedCompileJob::Status OptimizedCompileJob::CreateGraph() {
     return AbortOptimization(kFunctionBeingDebugged);
   }
 
+  // Do not use Crankshaft/TurboFan on a generator function.
+  // TODO(neis): Eventually enable for Turbofan.
+  if (IsGeneratorFunction(info()->shared_info()->kind())) {
+    return AbortOptimization(kGenerator);
+  }
+
   // Limit the number of times we try to optimize functions.
   const int kMaxOptCount =
       FLAG_deopt_every_n_times == 0 ? FLAG_max_opt_count : 1000;
@@ -550,8 +556,7 @@ bool CompileUnoptimizedCode(CompilationInfo* info) {
 }
 
 bool UseIgnition(CompilationInfo* info) {
-  // TODO(4681): Generator functions are not yet supported.
-  if (info->shared_info()->is_generator()) {
+  if (info->shared_info()->is_generator() && !FLAG_ignition_generators) {
     return false;
   }