Update V8 to r3431 as required by WebKit r51976.

Change-Id: I567392c3f8c0a0d5201a4249611ac4ccf468cd5b
diff --git a/src/arm/macro-assembler-arm.h b/src/arm/macro-assembler-arm.h
index e37bb5e..0974329 100644
--- a/src/arm/macro-assembler-arm.h
+++ b/src/arm/macro-assembler-arm.h
@@ -79,6 +79,11 @@
   void RecordWrite(Register object, Register offset, Register scratch);
 
   // ---------------------------------------------------------------------------
+  // Stack limit support
+
+  void StackLimitCheck(Label* on_stack_limit_hit);
+
+  // ---------------------------------------------------------------------------
   // Activation frames
 
   void EnterInternalFrame() { EnterFrame(StackFrame::INTERNAL); }
@@ -87,18 +92,20 @@
   void EnterConstructFrame() { EnterFrame(StackFrame::CONSTRUCT); }
   void LeaveConstructFrame() { LeaveFrame(StackFrame::CONSTRUCT); }
 
-  // Enter specific kind of exit frame; either EXIT or
-  // EXIT_DEBUG. Expects the number of arguments in register r0 and
+  // Enter specific kind of exit frame; either normal or debug mode.
+  // Expects the number of arguments in register r0 and
   // the builtin function to call in register r1. Exits with argc in
   // r4, argv in r6, and and the builtin function to call in r5.
-  void EnterExitFrame(StackFrame::Type type);
+  void EnterExitFrame(ExitFrame::Mode mode);
 
   // Leave the current exit frame. Expects the return value in r0.
-  void LeaveExitFrame(StackFrame::Type type);
+  void LeaveExitFrame(ExitFrame::Mode mode);
 
   // Align the stack by optionally pushing a Smi zero.
   void AlignStack(int offset);
 
+  void LoadContext(Register dst, int context_chain_length);
+
   // ---------------------------------------------------------------------------
   // JavaScript invokes
 
@@ -240,6 +247,11 @@
   // occurred.
   void IllegalOperation(int num_arguments);
 
+  // Uses VFP instructions to Convert a Smi to a double.
+  void IntegerToDoubleConversionWithVFP3(Register inReg,
+                                         Register outHighReg,
+                                         Register outLowReg);
+
 
   // ---------------------------------------------------------------------------
   // Runtime calls