Update V8 to r6122 (2.5 branch) as required by Chromium 9.0.597.55

Change-Id: Ia29dad551dd0cd7fa3c4d5084421f91d8b210271
diff --git a/src/arm/codegen-arm.cc b/src/arm/codegen-arm.cc
index 27e14df..06a4341 100644
--- a/src/arm/codegen-arm.cc
+++ b/src/arm/codegen-arm.cc
@@ -5672,6 +5672,12 @@
   __ tst(tmp2, Operand(kSmiTagMask));
   deferred->Branch(nz);
 
+  // Check that both indices are valid.
+  __ ldr(tmp2, FieldMemOperand(object, JSArray::kLengthOffset));
+  __ cmp(tmp2, index1);
+  __ cmp(tmp2, index2, hi);
+  deferred->Branch(ls);
+
   // Bring the offsets into the fixed array in tmp1 into index1 and
   // index2.
   __ mov(tmp2, Operand(FixedArray::kHeaderSize - kHeapObjectTag));
diff --git a/src/arm/full-codegen-arm.cc b/src/arm/full-codegen-arm.cc
index f04015b..0b6e13d 100644
--- a/src/arm/full-codegen-arm.cc
+++ b/src/arm/full-codegen-arm.cc
@@ -203,6 +203,11 @@
 }
 
 
+void FullCodeGenerator::ClearAccumulator() {
+  __ mov(r0, Operand(Smi::FromInt(0)));
+}
+
+
 void FullCodeGenerator::EmitReturnSequence() {
   Comment cmnt(masm_, "[ Return sequence");
   if (return_label_.is_bound()) {