Reland "Handle non-power-of-2 divisors in division-like operations".

src/a64/macro-assembler-a64.h

Index: src/a64/macro-assembler-a64.h
diff --git a/src/a64/macro-assembler-a64.h b/src/a64/macro-assembler-a64.h
index b11b9b688bc4f3c68a2b17cb5cd317b81cc2a6ce..81d0df62c8183f1a271ea06d39d41f959d7bd843 100644
--- a/src/a64/macro-assembler-a64.h
+++ b/src/a64/macro-assembler-a64.h
@@ -1677,6 +1677,10 @@ class MacroAssembler : public Assembler {
 
   void LoadContext(Register dst, int context_chain_length);
 
+  // Emit code for a flooring division by a constant. The dividend register is
+  // unchanged and Tmp0() gets clobbered. Dividend and result must be different.
+  void FlooringDiv(Register result, Register dividend, int32_t divisor);
+
   // ---------------------------------------------------------------------------
   // StatsCounter support