Update V8 to r4851 as required by WebKit r61121

Change-Id: Ib01b7c8e38d5b82b254192fc06365aa5b85780c5
diff --git a/src/globals.h b/src/globals.h
index 292d8d8..6cf2626 100644
--- a/src/globals.h
+++ b/src/globals.h
@@ -303,7 +303,6 @@
 class IC;
 class InterceptorInfo;
 class IterationStatement;
-class Array;
 class JSArray;
 class JSFunction;
 class JSObject;
@@ -544,16 +543,16 @@
 #define HAS_FAILURE_TAG(value) \
   ((reinterpret_cast<intptr_t>(value) & kFailureTagMask) == kFailureTag)
 
-// OBJECT_SIZE_ALIGN returns the value aligned HeapObject size
-#define OBJECT_SIZE_ALIGN(value)                                \
+// OBJECT_POINTER_ALIGN returns the value aligned as a HeapObject pointer
+#define OBJECT_POINTER_ALIGN(value)                             \
   (((value) + kObjectAlignmentMask) & ~kObjectAlignmentMask)
 
 // POINTER_SIZE_ALIGN returns the value aligned as a pointer.
 #define POINTER_SIZE_ALIGN(value)                               \
   (((value) + kPointerAlignmentMask) & ~kPointerAlignmentMask)
 
-// MAP_SIZE_ALIGN returns the value aligned as a map pointer.
-#define MAP_SIZE_ALIGN(value)                               \
+// MAP_POINTER_ALIGN returns the value aligned as a map pointer.
+#define MAP_POINTER_ALIGN(value)                                \
   (((value) + kMapAlignmentMask) & ~kMapAlignmentMask)
 
 // The expression OFFSET_OF(type, field) computes the byte-offset
@@ -648,7 +647,9 @@
 // Feature flags bit positions. They are mostly based on the CPUID spec.
 // (We assign CPUID itself to one of the currently reserved bits --
 // feel free to change this if needed.)
-enum CpuFeature { SSE3 = 32,   // x86
+// On X86/X64, values below 32 are bits in EDX, values above 32 are bits in ECX.
+enum CpuFeature { SSE4_1 = 32 + 19,  // x86
+                  SSE3 = 32 + 0,     // x86
                   SSE2 = 26,   // x86
                   CMOV = 15,   // x86
                   RDTSC = 4,   // x86