RFC: Switch to ast ids (instead of positions) for type feedback.

src/safepoint-table.h

Index: src/safepoint-table.h
diff --git a/src/safepoint-table.h b/src/safepoint-table.h
index 010ac5759bee7413ad27929783516209625aeafc..474aeba0dea9fba1c044e9ca6c6586f3984615e8 100644
--- a/src/safepoint-table.h
+++ b/src/safepoint-table.h
@@ -52,10 +52,10 @@ class SafepointTable BASE_EMBEDDED {
     return Memory::uint32_at(GetPcOffsetLocation(index));
   }
 
-  int GetDeoptimizationIndex(unsigned index) const {
+  AstId GetDeoptimizationIndex(unsigned index) const {
     ASSERT(index < length_);
     unsigned value = Memory::uint32_at(GetDeoptimizationLocation(index));
-    return DeoptimizationIndexField::decode(value);
+    return static_cast<AstId>(DeoptimizationIndexField::decode(value));
   }
 
   unsigned GetGapCodeSize(unsigned index) const {
@@ -114,7 +114,7 @@ class SafepointTable BASE_EMBEDDED {
 
 class Safepoint BASE_EMBEDDED {
  public:
-  static const int kNoDeoptimizationIndex = 0x00ffffff;
+  static const AstId kNoDeoptimizationIndex = 0x00ffffff;
 
   void DefinePointerSlot(int index) { indexes_->Add(index); }
   void DefinePointerRegister(Register reg) { registers_->Add(reg.code()); }