S390: Clean up the use of UNALIGNED_ACCESSES

BUG=

Review-Url: https://codereview.chromium.org/2249293002
Cr-Commit-Position: refs/heads/master@{#38670}

src/regexp/s390/regexp-macro-assembler-s390.cc

@@ -1226,13 +1226,9 @@ void RegExpMacroAssemblerS390::CallCFunctionUsingStub(
   __ mov(code_pointer(), Operand(masm_->CodeObject()));
 }
 
-bool RegExpMacroAssemblerS390::CanReadUnaligned() {
-  return CpuFeatures::IsSupported(UNALIGNED_ACCESSES) && !slow_safe();
-}
 
 void RegExpMacroAssemblerS390::LoadCurrentCharacterUnchecked(int cp_offset,
                                                              int characters) {
-  DCHECK(characters == 1 || CanReadUnaligned());
   if (mode_ == LATIN1) {
     // using load reverse for big-endian platforms
     if (characters == 4) {

src/regexp/s390/regexp-macro-assembler-s390.h

@@ -77,7 +77,6 @@ class RegExpMacroAssemblerS390 : public NativeRegExpMacroAssembler {
   virtual void WriteCurrentPositionToRegister(int reg, int cp_offset);
   virtual void ClearRegisters(int reg_from, int reg_to);
   virtual void WriteStackPointerToRegister(int reg);
-  virtual bool CanReadUnaligned();
 
   // Called from RegExp if the stack-guard is triggered.
   // If the code object is relocated, the return address is fixed before

src/s390/assembler-s390.cc

@@ -173,7 +173,6 @@ void CpuFeatures::ProbeImpl(bool cross_compile) {
   USE(performSTFLE);  // To avoid assert
 #endif
   supported_ |= (1u << FPU);
-  supported_ |= (1u << UNALIGNED_ACCESSES);
 }
 
 void CpuFeatures::PrintTarget() {