[crankshaft] Support inlining of function calls in tail position (in ES6 sense).

src/crankshaft/lithium.cc

Index: src/crankshaft/lithium.cc
diff --git a/src/crankshaft/lithium.cc b/src/crankshaft/lithium.cc
index a1a73e4beb84042075fdf72be63a93ea8b170a06..12e1f5fe2473520366d5e446103fedbab4d8c19b 100644
--- a/src/crankshaft/lithium.cc
+++ b/src/crankshaft/lithium.cc
@@ -529,6 +529,12 @@ LEnvironment* LChunkBuilderBase::CreateEnvironment(
   DCHECK(!ast_id.IsNone() ||
          hydrogen_env->frame_type() != JS_FUNCTION);

[Michael Starzinger, 2016/03/21 14:06:50]

nit: I think this DCHECK can be made stronger ...

DCHECK(!ast_id.IsNone() ||
       (hydrogen_env->frame_type() != JS_FUNCTION &&
        hydrogen_env->frame_type() != TAIL_CALLER_FUNCTION));

[Igor Sheludko, 2016/03/22 14:08:37]

Done.

 
+  if (hydrogen_env->frame_type() == TAIL_CALLER_FUNCTION) {
+    return new (zone())
+        LEnvironment(hydrogen_env->closure(), hydrogen_env->frame_type(),
+                     ast_id, 0, 0, 0, outer, hydrogen_env->entry(), zone());
+  }
+
   int omitted_count = (hydrogen_env->frame_type() == JS_FUNCTION)
                           ? 0
                           : hydrogen_env->specials_count();