[macro-assembler] Delete unused SmiOperationConstraint

Bug: v8:6921
Change-Id: I1bd9e5425ddad59ae9ac25c5eb6f05472072a358
Reviewed-on: https://chromium-review.googlesource.com/718103Reviewed-by: Igor Sheludko <ishell@chromium.org>
Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Commit-Queue: Toon Verwaest <verwaest@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48528}

src/x64/macro-assembler-x64.h

@@ -45,18 +45,8 @@ typedef Operand MemOperand;
 enum RememberedSetAction { EMIT_REMEMBERED_SET, OMIT_REMEMBERED_SET };
 enum SmiCheck { INLINE_SMI_CHECK, OMIT_SMI_CHECK };
 
-enum class SmiOperationConstraint {
-  kPreserveSourceRegister = 1 << 0,
-  kBailoutOnNoOverflow = 1 << 1,
-  kBailoutOnOverflow = 1 << 2
-};
-
 enum class ReturnAddressState { kOnStack, kNotOnStack };
 
-typedef base::Flags<SmiOperationConstraint> SmiOperationConstraints;
-
-DEFINE_OPERATORS_FOR_FLAGS(SmiOperationConstraints)
-
 #ifdef DEBUG
 bool AreAliased(Register reg1,
                 Register reg2,