Roll V8 back to 3.6

Roll back to V8 3.6 to fix x86 build, we don't have ucontext.h.

This reverts commits:
5d4cdbf7a67d3662fa0bee4efdb7edd8daec9b0b
c7cc028aaeedbbfa11c11d0b7b243b3d9e837ed9
592a9fc1d8ea420377a2e7efd0600e20b058be2b

Bug: 5688872
Change-Id: Ic961bb5e65b778e98bbfb71cce71d99fa949e995
diff --git a/src/string-stream.cc b/src/string-stream.cc
index 35f7be5..8086cf9 100644
--- a/src/string-stream.cc
+++ b/src/string-stream.cc
@@ -350,24 +350,29 @@
   }
   DescriptorArray* descs = map->instance_descriptors();
   for (int i = 0; i < descs->number_of_descriptors(); i++) {
-    if (descs->GetType(i) == FIELD) {
-      Object* key = descs->GetKey(i);
-      if (key->IsString() || key->IsNumber()) {
-        int len = 3;
-        if (key->IsString()) {
-          len = String::cast(key)->length();
+    switch (descs->GetType(i)) {
+      case FIELD: {
+        Object* key = descs->GetKey(i);
+        if (key->IsString() || key->IsNumber()) {
+          int len = 3;
+          if (key->IsString()) {
+            len = String::cast(key)->length();
+          }
+          for (; len < 18; len++)
+            Put(' ');
+          if (key->IsString()) {
+            Put(String::cast(key));
+          } else {
+            key->ShortPrint();
+          }
+          Add(": ");
+          Object* value = js_object->FastPropertyAt(descs->GetFieldIndex(i));
+          Add("%o\n", value);
         }
-        for (; len < 18; len++)
-          Put(' ');
-        if (key->IsString()) {
-          Put(String::cast(key));
-        } else {
-          key->ShortPrint();
-        }
-        Add(": ");
-        Object* value = js_object->FastPropertyAt(descs->GetFieldIndex(i));
-        Add("%o\n", value);
       }
+      break;
+      default:
+      break;
     }
   }
 }