[runtime] Support Proxy setPrototypeOf trap

src/ast/variables.cc

Index: src/ast/variables.cc
diff --git a/src/ast/variables.cc b/src/ast/variables.cc
index 8e007823863aea9e403252fa891b59866b708929..34cab4d4dfe22ccfe0a5804319a4c4176c82498f 100644
--- a/src/ast/variables.cc
+++ b/src/ast/variables.cc
@@ -15,15 +15,24 @@ namespace internal {
 
 const char* Variable::Mode2String(VariableMode mode) {
   switch (mode) {
-    case VAR: return "VAR";
-    case CONST_LEGACY: return "CONST_LEGACY";
-    case LET: return "LET";
-    case CONST: return "CONST";
-    case IMPORT: return "IMPORT";
-    case DYNAMIC: return "DYNAMIC";
-    case DYNAMIC_GLOBAL: return "DYNAMIC_GLOBAL";
-    case DYNAMIC_LOCAL: return "DYNAMIC_LOCAL";
-    case TEMPORARY: return "TEMPORARY";
+    case VAR:
+      return "VAR";
+    case CONST_LEGACY:
+      return "CONST_LEGACY";
+    case LET:
+      return "LET";
+    case CONST:
+      return "CONST";
+    case IMPORT:
+      return "IMPORT";
+    case DYNAMIC:
+      return "DYNAMIC";
+    case DYNAMIC_GLOBAL:
+      return "DYNAMIC_GLOBAL";
+    case DYNAMIC_LOCAL:
+      return "DYNAMIC_LOCAL";
+    case TEMPORARY:
+      return "TEMPORARY";
   }
   UNREACHABLE();
   return NULL;