[turbofan] Turn DCHECK for fixed slot index into a CHECK.

src/compiler/instruction.h

Index: src/compiler/instruction.h
diff --git a/src/compiler/instruction.h b/src/compiler/instruction.h
index 41cda82fc1b204921532ca2defd17baa40bd1a0b..4ce89ddd97ce193118d9736cfd5058c305e034ef 100644
--- a/src/compiler/instruction.h
+++ b/src/compiler/instruction.h
@@ -129,7 +129,8 @@ class UnallocatedOperand : public InstructionOperand {
     value_ |= VirtualRegisterField::encode(kInvalidVirtualRegister);
     value_ |= BasicPolicyField::encode(policy);
     value_ |= index << FixedSlotIndexField::kShift;
-    DCHECK(this->fixed_slot_index() == index);
+    // TODO(dcarney): 2^10 is not enough for the fixed slot index.
+    CHECK(this->fixed_slot_index() == index);
   }
 
   UnallocatedOperand(ExtendedPolicy policy, int index)