Revert "A simpler scheme for garbage collection of ureachable phi inputs."

runtime/vm/growable_array.h

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 // Defines growable array classes, that differ where they are allocated:
 // - GrowableArray: allocate on stack.
 // - ZoneGrowableArray: allocated in the zone.
 
 #ifndef VM_GROWABLE_ARRAY_H_
 #define VM_GROWABLE_ARRAY_H_
 
@@ skipping 55 matching lines @@
   void AddArray(const BaseGrowableArray<T, B>& src) {
     for (intptr_t i = 0; i < src.length(); i++) {
       Add(src[i]);
     }
   }
 
   void Clear() {
     length_ = 0;
   }
 
+  void RemoveFirst() {
+    ASSERT(length_ > 0);
+    length_--;
+    for (int i = 0; i < length_; i++) {
+      data_[i] = data_[i + 1];
+    }
+  }
+
   void InsertAt(intptr_t idx, const T& value) {
     Resize(length() + 1);
     for (intptr_t i = length_ - 2; i >= idx; i--) {
       data_[i + 1] = data_[i];
     }
     data_[idx] = value;
   }
 
   // Sort the array in place.
   inline void Sort(int compare(const T*, const T*));
@@ skipping 52 matching lines @@
           initial_capacity,
           Isolate::Current()->current_zone()->GetBaseZone()) {}
   ZoneGrowableArray() :
       BaseGrowableArray<T, ZoneAllocated>(
           Isolate::Current()->current_zone()->GetBaseZone()) {}
 };
 
 }  // namespace dart
 
 #endif  // VM_GROWABLE_ARRAY_H_