Introduce {FAST,SLOW}_STRING_WRAPPER_ELEMENTS

src/crankshaft/x64/lithium-codegen-x64.cc

Index: src/crankshaft/x64/lithium-codegen-x64.cc
diff --git a/src/crankshaft/x64/lithium-codegen-x64.cc b/src/crankshaft/x64/lithium-codegen-x64.cc
index 695c19777bd47ee1673d62f8ef7c0f315bcac34b..059969a2029b2788f3811d699f39641b1b1313f8 100644
--- a/src/crankshaft/x64/lithium-codegen-x64.cc
+++ b/src/crankshaft/x64/lithium-codegen-x64.cc
@@ -2903,6 +2903,9 @@ void LCodeGen::DoLoadKeyedExternalArray(LLoadKeyed* instr) {
       case DICTIONARY_ELEMENTS:
       case FAST_SLOPPY_ARGUMENTS_ELEMENTS:
       case SLOW_SLOPPY_ARGUMENTS_ELEMENTS:
+      case FAST_STRING_WRAPPER_ELEMENTS:
+      case SLOW_STRING_WRAPPER_ELEMENTS:
+      case NO_ELEMENTS:
         UNREACHABLE();
         break;
     }
@@ -4101,6 +4104,9 @@ void LCodeGen::DoStoreKeyedExternalArray(LStoreKeyed* instr) {
       case DICTIONARY_ELEMENTS:
       case FAST_SLOPPY_ARGUMENTS_ELEMENTS:
       case SLOW_SLOPPY_ARGUMENTS_ELEMENTS:
+      case FAST_STRING_WRAPPER_ELEMENTS:
+      case SLOW_STRING_WRAPPER_ELEMENTS:
+      case NO_ELEMENTS:
         UNREACHABLE();
         break;
     }