Update V8 to r4588

We're using WebKit r58033, as used by
http://src.chromium.org/svn/releases/5.0.387.0/DEPS
This requires http://v8.googlecode.com/svn/trunk@4465 but this version has a
crashing bug for ARM. Instead we use http://v8.googlecode.com/svn/trunk@4588,
which is used by http://src.chromium.org/svn/releases/6.0.399.0/DEPS

Note that a trivial bug fix was required in arm/codegen-arm.cc. This is guarded
with ANDROID. See http://code.google.com/p/v8/issues/detail?id=703

Change-Id: I459647a8286c4f8c7405f0c5581ecbf051a6f1e8
diff --git a/src/log-utils.cc b/src/log-utils.cc
index 722e0fc..62f0ca6 100644
--- a/src/log-utils.cc
+++ b/src/log-utils.cc
@@ -196,6 +196,9 @@
   char* end_pos = dest_buf + actual_size - 1;
   while (end_pos >= dest_buf && *end_pos != '\n') --end_pos;
   actual_size = static_cast<int>(end_pos - dest_buf + 1);
+  // If the assertion below is hit, it means that there was no line end
+  // found --- something wrong has happened.
+  ASSERT(actual_size > 0);
   ASSERT(actual_size <= max_size);
   return actual_size;
 }