Crankshaft is now able to compile top level code even if there is a ScriptContext.

src/x64/lithium-codegen-x64.cc

Index: src/x64/lithium-codegen-x64.cc
diff --git a/src/x64/lithium-codegen-x64.cc b/src/x64/lithium-codegen-x64.cc
index c085fa058883c13ec81a9718b4a7bc08f30a6c58..4e1ac86aefcd18b8d754458b060eeea17812a23c 100644
--- a/src/x64/lithium-codegen-x64.cc
+++ b/src/x64/lithium-codegen-x64.cc
@@ -185,16 +185,27 @@ bool LCodeGen::GeneratePrologue() {
       SaveCallerDoubles();
     }
   }
+  return !is_aborted();
+}
+
+
+void LCodeGen::DoPrologue(LPrologue* instr) {
+  Comment(";;; Prologue begin");
 
   // Possibly allocate a local context.
-  int heap_slots = info_->num_heap_slots() - Context::MIN_CONTEXT_SLOTS;
-  if (heap_slots > 0) {
+  if (info_->num_heap_slots() > 0) {
     Comment(";;; Allocate local context");
     bool need_write_barrier = true;
     // Argument to NewContext is the function, which is still in rdi.
-    DCHECK(!info()->scope()->is_script_scope());
-    if (heap_slots <= FastNewContextStub::kMaximumSlots) {
-      FastNewContextStub stub(isolate(), heap_slots);
+    int slots = info_->num_heap_slots() - Context::MIN_CONTEXT_SLOTS;
+    Safepoint::DeoptMode deopt_mode = Safepoint::kNoLazyDeopt;
+    if (info()->scope()->is_script_scope()) {
+      __ Push(rdi);
+      __ Push(info()->scope()->GetScopeInfo(info()->isolate()));
+      __ CallRuntime(Runtime::kNewScriptContext, 2);
+      deopt_mode = Safepoint::kLazyDeopt;
+    } else if (slots <= FastNewContextStub::kMaximumSlots) {
+      FastNewContextStub stub(isolate(), slots);
       __ CallStub(&stub);
       // Result of FastNewContextStub is always in new space.
       need_write_barrier = false;
@@ -202,7 +213,8 @@ bool LCodeGen::GeneratePrologue() {
       __ Push(rdi);
       __ CallRuntime(Runtime::kNewFunctionContext, 1);
     }
-    RecordSafepoint(Safepoint::kNoLazyDeopt);
+    RecordSafepoint(deopt_mode);
+
     // Context is returned in rax.  It replaces the context passed to us.
     // It's saved in the stack and kept live in rsi.
     __ movp(rsi, rax);
@@ -235,11 +247,7 @@ bool LCodeGen::GeneratePrologue() {
     Comment(";;; End allocate local context");
   }
 
-  // Trace the call.
-  if (FLAG_trace && info()->IsOptimizing()) {
-    __ CallRuntime(Runtime::kTraceEnter, 0);
-  }
-  return !is_aborted();
+  Comment(";;; Prologue end");
 }