Fix maybe_string_add for adds that have no type feedback where --always-opt is on.

test/test262-es6/test262-es6.status

 # Copyright 2011 the V8 project authors. All rights reserved.
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met:
 #
 #     * Redistributions of source code must retain the above copyright
 #       notice, this list of conditions and the following disclaimer.
 #     * Redistributions in binary form must reproduce the above
 #       copyright notice, this list of conditions and the following
 #       disclaimer in the documentation and/or other materials provided
@@ skipping 15 matching lines @@
 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 [
 [ALWAYS, {
   ############################### BUGS ###################################
 
   # BUG(v8:3455)
   'intl402/11.2.3_b': [FAIL],
   'intl402/12.2.3_b': [FAIL],
 
-  # TODO(mstarzinger): Optimizing top-level code found some issues. Fix!
-  'language/expressions/addition/S11.6.1_A2.2_T2': [PASS, NO_VARIANTS],
-  'language/expressions/addition/S11.6.1_A3.2_T2.2': [PASS, NO_VARIANTS],
-  'language/expressions/addition/S11.6.1_A3.2_T2.4': [PASS, NO_VARIANTS],
-
   # Unicode canonicalization is not available with i18n turned off.
   'built-ins/String/prototype/localeCompare/15.5.4.9_CE': [['no_i18n', SKIP]],
 
   ###################### NEEDS INVESTIGATION #######################
 
   # Possibly same cause as S8.5_A2.1, below: floating-point tests.
   'built-ins/Math/sin/S15.8.2.16_A7': [PASS, FAIL_OK],
   'built-ins/Math/tan/S15.8.2.18_A7': [PASS, FAIL_OK],
   'built-ins/Math/cos/S15.8.2.7_A7': [PASS, FAIL_OK],
 
@@ skipping 622 matching lines @@
 
   # BUG(3251225): Tests that timeout with --nocrankshaft.
   'built-ins/decodeURI/S15.1.3.1_A2.4_T1': [SKIP],
   'built-ins/decodeURI/S15.1.3.1_A2.5_T1': [SKIP],
   'built-ins/decodeURIComponent/S15.1.3.2_A2.4_T1': [SKIP],
   'built-ins/decodeURIComponent/S15.1.3.2_A2.5_T1': [SKIP],
   'built-ins/encodeURI/S15.1.3.3_A2.3_T1': [SKIP],
   'built-ins/encodeURIComponent/S15.1.3.4_A2.3_T1': [SKIP],
 }],  # 'arch == arm or arch == mipsel or arch == mips or arch == arm64'
 ]