[turbofan] Implement OSR for outer loops.

src/compiler/scheduler.cc

Index: src/compiler/scheduler.cc
diff --git a/src/compiler/scheduler.cc b/src/compiler/scheduler.cc
index 96d1c3715f6e956c82154218eca3021a994740c1..9e62aa6b6022da8b94a8d466867ad56138195d0b 100644
--- a/src/compiler/scheduler.cc
+++ b/src/compiler/scheduler.cc
@@ -75,7 +75,8 @@ Scheduler::Placement Scheduler::GetPlacement(Node* node) {
   if (data->placement_ == kUnknown) {  // Compute placement, once, on demand.
     switch (node->opcode()) {
       case IrOpcode::kParameter:
-        // Parameters are always fixed to the start node.
+      case IrOpcode::kOsrValue:
+        // Parameters and OSR values are always fixed to the start block.
         data->placement_ = kFixed;
         break;
       case IrOpcode::kPhi: