Introduce {FAST,SLOW}_STRING_WRAPPER_ELEMENTS

src/crankshaft/mips64/lithium-codegen-mips64.cc

Index: src/crankshaft/mips64/lithium-codegen-mips64.cc
diff --git a/src/crankshaft/mips64/lithium-codegen-mips64.cc b/src/crankshaft/mips64/lithium-codegen-mips64.cc
index e50c095b6919b2cfcf121080ec291441d3795fd5..333f8300bf96fa582a12fe6fee04e04983143a8c 100644
--- a/src/crankshaft/mips64/lithium-codegen-mips64.cc
+++ b/src/crankshaft/mips64/lithium-codegen-mips64.cc
@@ -3020,6 +3020,9 @@ 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;
     }
@@ -4194,6 +4197,9 @@ 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;
     }