Merge V8 at 2.5.9.19

Pull in the latest V8 for various stability fixes.

Note that this deviates from the Chromium 9.0.597.x branch.

Bug: 3483676
Change-Id: I06d94f1d178d76395fe437a9ac01a4c71f0fada9
diff --git a/src/version.cc b/src/version.cc
index 041facd..fbbfe59 100644
--- a/src/version.cc
+++ b/src/version.cc
@@ -35,7 +35,7 @@
 #define MAJOR_VERSION     2
 #define MINOR_VERSION     5
 #define BUILD_NUMBER      9
-#define PATCH_LEVEL       15
+#define PATCH_LEVEL       19
 #define CANDIDATE_VERSION false
 
 // Define SONAME to have the SCons build the put a specific SONAME into the