MIPS: Reland "Fixed environment assignment for LCheckNonSmi."

src/mips/lithium-mips.cc

Index: src/mips/lithium-mips.cc
diff --git a/src/mips/lithium-mips.cc b/src/mips/lithium-mips.cc
index 6ce4ba345535f5aef9839459bf4613e8910f0d8e..e4a7a65d6501b1c5e5eef525128e066cbbaf5da9 100644
--- a/src/mips/lithium-mips.cc
+++ b/src/mips/lithium-mips.cc
@@ -1913,7 +1913,9 @@ LInstruction* LChunkBuilder::DoChange(HChange* instr) {
 
 LInstruction* LChunkBuilder::DoCheckHeapObject(HCheckHeapObject* instr) {
   LOperand* value = UseRegisterAtStart(instr->value());
-  return AssignEnvironment(new(zone()) LCheckNonSmi(value));
+  LInstruction* result = new(zone()) LCheckNonSmi(value);
+  if (!instr->value()->IsHeapObject()) result = AssignEnvironment(result);
+  return result;
 }