More simplification and unification of frame handling

src/crankshaft/x64/lithium-x64.cc

Index: src/crankshaft/x64/lithium-x64.cc
diff --git a/src/crankshaft/x64/lithium-x64.cc b/src/crankshaft/x64/lithium-x64.cc
index 171a58115ae9c58499725b8d151fe5ce56875a03..c4ec47b07fa9e1d3c91a65d09ff714775676d3c8 100644
--- a/src/crankshaft/x64/lithium-x64.cc
+++ b/src/crankshaft/x64/lithium-x64.cc
@@ -334,15 +334,15 @@ void LAccessArgumentsAt::PrintDataTo(StringStream* stream) {
 int LPlatformChunk::GetNextSpillIndex(RegisterKind kind) {
   if (kind == DOUBLE_REGISTERS && kDoubleSize == 2 * kPointerSize) {
     // Skip a slot if for a double-width slot for x32 port.
-    spill_slot_count_++;
+    current_frame_slots_++;
     // The spill slot's address is at rbp - (index + 1) * kPointerSize -
     // StandardFrameConstants::kFixedFrameSizeFromFp. kFixedFrameSizeFromFp is
     // 2 * kPointerSize, if rbp is aligned at 8-byte boundary, the below "|= 1"
     // will make sure the spilled doubles are aligned at 8-byte boundary.
     // TODO(haitao): make sure rbp is aligned at 8-byte boundary for x32 port.
-    spill_slot_count_ |= 1;
+    current_frame_slots_ |= 1;
   }
-  return spill_slot_count_++;
+  return current_frame_slots_++;
 }
 
 
@@ -2501,6 +2501,7 @@ LInstruction* LChunkBuilder::DoUnknownOSRValue(HUnknownOSRValue* instr) {
       Retry(kTooManySpillSlotsNeededForOSR);
       spill_index = 0;
     }
+    spill_index += StandardFrameConstants::kFixedSlotCount;
   }
   return DefineAsSpilled(new(zone()) LUnknownOSRValue, spill_index);
 }