Reland parts of 'Use weak cells in map checks in polymorphic ICs'

src/arm/macro-assembler-arm.h

Index: src/arm/macro-assembler-arm.h
diff --git a/src/arm/macro-assembler-arm.h b/src/arm/macro-assembler-arm.h
index 79d26f2696cd4c729c49b85eaf52e099e661b3d4..8e1c1127b8fcdccb2cb4b012a1db97f61c6a8d49 100644
--- a/src/arm/macro-assembler-arm.h
+++ b/src/arm/macro-assembler-arm.h
@@ -927,6 +927,12 @@ class MacroAssembler: public Assembler {
                    Handle<Code> success,
                    SmiCheckType smi_check_type);
 
+  // Compare the given value and the value of weak cell.
+  void CmpWeakValue(Register value, Handle<WeakCell> cell, Register scratch);
+
+  // Load the value of the weak cell in the value register. Branch to the given
+  // miss label if the weak cell was cleared.
+  void LoadWeakValue(Register value, Handle<WeakCell> cell, Label* miss);
 
   // Compare the object in a register to a value from the root list.
   // Uses the ip register as scratch.