Revert "- Make ports be less predictable."

runtime/vm/port.cc

Index: runtime/vm/port.cc
diff --git a/runtime/vm/port.cc b/runtime/vm/port.cc
index 037d55ac91b4ef54a90ddc2e3f4957699cb2c72a..0c9a627bb4ce27ede7e6a6fdaa8ea5be3d3468a2 100644
--- a/runtime/vm/port.cc
+++ b/runtime/vm/port.cc
@@ -20,7 +20,7 @@ MessageHandler* PortMap::deleted_entry_ = reinterpret_cast<MessageHandler*>(1);
 intptr_t PortMap::capacity_ = 0;
 intptr_t PortMap::used_ = 0;
 intptr_t PortMap::deleted_ = 0;
-Random* PortMap::prng_ = NULL;
+Dart_Port PortMap::next_port_ = 7111;
 
 
 intptr_t PortMap::FindPort(Dart_Port port) {
@@ -63,11 +63,13 @@ void PortMap::Rehash(intptr_t new_capacity) {
 
 
 Dart_Port PortMap::AllocatePort() {
-  Dart_Port result = prng_->NextUInt32() & kSmiMax;
+  Dart_Port result = next_port_;
 
-  while ((result == 0) && (FindPort(result) >= 0)) {
-    result = prng_->NextUInt32() & kSmiMax;
-  }
+  do {
+    // TODO(iposva): Use an approved hashing function to have less predictable
+    // port ids, or make them not accessible from Dart code or both.
+    next_port_++;
+  } while (FindPort(next_port_) >= 0);
 
   ASSERT(result != 0);
   return result;
@@ -256,7 +258,6 @@ Isolate* PortMap::GetIsolate(Dart_Port id) {
 
 void PortMap::InitOnce() {
   mutex_ = new Mutex();
-  prng_ = new Random();
 
   static const intptr_t kInitialCapacity = 8;
   // TODO(iposva): Verify whether we want to keep exponentially growing.