Use a random seed for the string hash algorithm.

src/isolate.cc

Index: src/isolate.cc
===================================================================
--- src/isolate.cc	(revision 10321)
+++ src/isolate.cc	(working copy)
@@ -1437,7 +1437,8 @@
       has_installed_extensions_(false),
       string_tracker_(NULL),
       regexp_stack_(NULL),
-      embedder_data_(NULL) {
+      embedder_data_(NULL),
+      hasher_seed_(0) {
   TRACE_ISOLATE(constructor);
 
   memset(isolate_addresses_, 0,
@@ -1733,6 +1734,16 @@
   regexp_stack_ = new RegExpStack();
   regexp_stack_->isolate_ = this;
 
+  // Setup the seed that is used to randomize the string hash function.
+  ASSERT(hasher_seed_ == 0);
+  if (FLAG_randomize_string_hashes) {
+    if (FLAG_string_hash_seed == 0) {
+      hasher_seed_ = V8::RandomPrivate(this);
+    } else {
+      hasher_seed_ = FLAG_string_hash_seed;
+    }
+  }
+
   // Enable logging before setting up the heap
   logger_->Setup();