Update V8 to version 4.1.0.21

This is a cherry-pick of all commits up to and including the
4.1.0.21 cherry-pick in Chromium.

Original commit message:

Version 4.1.0.21 (cherry-pick)

Merged 206e9136bde0f2b5ae8cb77afbb1e7833e5bd412

Unlink pages from the space page list after evacuation.

BUG=430201
LOG=N
R=jkummerow@chromium.org

Review URL: https://codereview.chromium.org/953813002

Cr-Commit-Position: refs/branch-heads/4.1@{#22}
Cr-Branched-From: 2e08d2a7aa9d65d269d8c57aba82eb38a8cb0a18-refs/heads/candidates@{#25353}

---

FPIIM-449

Change-Id: I8c23c7bbb70772b4858fe8a47b64fa97ee0d1f8c
diff --git a/src/heap/heap-inl.h b/src/heap/heap-inl.h
index e658224..549ecbc 100644
--- a/src/heap/heap-inl.h
+++ b/src/heap/heap-inl.h
@@ -458,8 +458,6 @@
     case PROPERTY_CELL_SPACE:
     case LO_SPACE:
       return false;
-    case INVALID_SPACE:
-      break;
   }
   UNREACHABLE();
   return false;
@@ -589,7 +587,7 @@
 Isolate* Heap::isolate() {
   return reinterpret_cast<Isolate*>(
       reinterpret_cast<intptr_t>(this) -
-      reinterpret_cast<size_t>(reinterpret_cast<Isolate*>(4)->heap()) + 4);
+      reinterpret_cast<size_t>(reinterpret_cast<Isolate*>(16)->heap()) + 16);
 }
 
 
@@ -699,7 +697,7 @@
 
 
 void Heap::ClearInstanceofCache() {
-  set_instanceof_cache_function(the_hole_value());
+  set_instanceof_cache_function(Smi::FromInt(0));
 }
 
 
@@ -709,8 +707,8 @@
 
 
 void Heap::CompletelyClearInstanceofCache() {
-  set_instanceof_cache_map(the_hole_value());
-  set_instanceof_cache_function(the_hole_value());
+  set_instanceof_cache_map(Smi::FromInt(0));
+  set_instanceof_cache_function(Smi::FromInt(0));
 }