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/arm64/assembler-arm64.h b/src/arm64/assembler-arm64.h
index 82b4500..53496f3 100644
--- a/src/arm64/assembler-arm64.h
+++ b/src/arm64/assembler-arm64.h
@@ -276,6 +276,11 @@
       (kAllocatableHighRangeEnd - kAllocatableHighRangeBegin + 1);
   static int NumAllocatableRegisters() { return kMaxNumAllocatableRegisters; }
 
+  // TODO(turbofan): Proper float32 support.
+  static int NumAllocatableAliasedRegisters() {
+    return NumAllocatableRegisters();
+  }
+
   // Return true if the register is one that crankshaft can allocate.
   bool IsAllocatable() const {
     return (Bit() & kAllocatableFPRegisters) != 0;
@@ -1658,6 +1663,9 @@
   // FP round to integer (nearest with ties to even).
   void frintn(const FPRegister& fd, const FPRegister& fn);
 
+  // FP round to integer (towards plus infinity).
+  void frintp(const FPRegister& fd, const FPRegister& fn);
+
   // FP round to integer (towards zero.)
   void frintz(const FPRegister& fd, const FPRegister& fn);