[generators] Add asserts preventing mixed functions.

src/runtime/runtime-generator.cc

Index: src/runtime/runtime-generator.cc
diff --git a/src/runtime/runtime-generator.cc b/src/runtime/runtime-generator.cc
index 198bf4b82cbd81c0e5c50c9d67f27857f9e1db30..dcc48c5c9e09b112d4596166253a2aaa7e6b5db2 100644
--- a/src/runtime/runtime-generator.cc
+++ b/src/runtime/runtime-generator.cc
@@ -23,10 +23,12 @@ RUNTIME_FUNCTION(Runtime_CreateJSGeneratorObject) {
   Handle<FixedArray> operand_stack;
   if (function->shared()->HasBytecodeArray()) {
     // New-style generators.
+    DCHECK(!function->shared()->HasBaselineCode());
     int size = function->shared()->bytecode_array()->register_count();
     operand_stack = isolate->factory()->NewFixedArray(size);
   } else {
     // Old-style generators.
+    DCHECK(function->shared()->HasBaselineCode());
     operand_stack = isolate->factory()->empty_fixed_array();
   }