Update V8 to r5017 as required by WebKit r62496

Change-Id: I1b4b7718d1d77ceef07f543e9150a2cb3a628f3a
diff --git a/src/regexp-macro-assembler.cc b/src/regexp-macro-assembler.cc
index fc65947..09797ca 100644
--- a/src/regexp-macro-assembler.cc
+++ b/src/regexp-macro-assembler.cc
@@ -120,8 +120,6 @@
   int start_offset = previous_index;
   int end_offset = subject_ptr->length();
 
-  bool is_ascii = subject->IsAsciiRepresentation();
-
   // The string has been flattened, so it it is a cons string it contains the
   // full string in the first part.
   if (StringShape(subject_ptr).IsCons()) {
@@ -129,7 +127,7 @@
     subject_ptr = ConsString::cast(subject_ptr)->first();
   }
   // Ensure that an underlying string has the same ascii-ness.
-  ASSERT(subject_ptr->IsAsciiRepresentation() == is_ascii);
+  bool is_ascii = subject_ptr->IsAsciiRepresentation();
   ASSERT(subject_ptr->IsExternalString() || subject_ptr->IsSeqString());
   // String is now either Sequential or External
   int char_size_shift = is_ascii ? 0 : 1;