Randomize the seed used for string hashing. This helps guard against

src/ia32/code-stubs-ia32.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 6015 matching lines @@
   if (!result.is(eax)) {
     __ mov(eax, result);
   }
 }
 
 
 void StringHelper::GenerateHashInit(MacroAssembler* masm,
                                     Register hash,
                                     Register character,
                                     Register scratch) {
-  // hash = character + (character << 10);
-  __ mov(hash, character);
-  __ shl(hash, 10);
-  __ add(hash, character);
+  // hash = (seed + character) + ((seed + character) << 10);
+  if (Serializer::enabled()) {
+    ExternalReference roots_array_start =
+        ExternalReference::roots_array_start(masm->isolate());
+    __ mov(scratch, Immediate(Heap::kStringHashSeedRootIndex));
+    __ mov(scratch, Operand::StaticArray(scratch,
+                                         times_pointer_size,
+                                         roots_array_start));
+    __ add(scratch, character);
+    __ mov(hash, scratch);
+    __ shl(scratch, 10);
+    __ add(hash, scratch);
+  } else {
+    int32_t seed = masm->isolate()->heap()->StringHashSeed();
+    __ lea(scratch, Operand(character, seed));
+    __ shl(scratch, 10);
+    __ lea(hash, Operand(scratch, character, times_1, seed));
+  }
   // hash ^= hash >> 6;
   __ mov(scratch, hash);
   __ shr(scratch, 6);
   __ xor_(hash, scratch);
 }
 
 
 void StringHelper::GenerateHashAddCharacter(MacroAssembler* masm,
                                             Register hash,
                                             Register character,
@@ skipping 1282 matching lines @@
                                  false);
   __ pop(edx);
   __ ret(0);
 }
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32