Add SetLength to GrowableArray and use it in code coverage.

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: allocated on stack.
 // - ZoneGrowableArray: allocated in the zone.
 
 #ifndef VM_GROWABLE_ARRAY_H_
 #define VM_GROWABLE_ARRAY_H_
 
@@ skipping 65 matching lines @@
   }
 
   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;
   }
 
+  // The content is uninitialized after calling it.
+  void SetLength(intptr_t new_length);
+
   // Sort the array in place.
   inline void Sort(int compare(const T*, const T*));
 
  private:
   intptr_t length_;
   intptr_t capacity_;
   T* data_;
   Zone* zone_;  // Zone in which we are allocating the array.
 
+  // Used for growing the array.
   void Resize(intptr_t new_length);
 
   DISALLOW_COPY_AND_ASSIGN(BaseGrowableArray);
 };
 
 
 template<typename T, typename B>
 inline void BaseGrowableArray<T, B>::Sort(
     int compare(const T*, const T*)) {
   typedef int (*CompareFunction)(const void*, const void*);
   qsort(data_, length_, sizeof(T), reinterpret_cast<CompareFunction>(compare));
 }
 
 
 template<typename T, typename B>
 void BaseGrowableArray<T, B>::Resize(intptr_t new_length) {
   if (new_length > capacity_) {
     intptr_t new_capacity = Utils::RoundUpToPowerOfTwo(new_length);
     T* new_data = zone_->Realloc<T>(data_, capacity_, new_capacity);
     ASSERT(new_data != NULL);
     data_ = new_data;
     capacity_ = new_capacity;
   }
   length_ = new_length;
 }
 
 
+template<typename T, typename B>
+void BaseGrowableArray<T, B>::SetLength(intptr_t new_length) {
+  if (new_length > capacity_) {
+    T* new_data = zone_->Alloc<T>(new_length);
+    ASSERT(new_data != NULL);
+    data_ = new_data;
+    capacity_ = new_length;
+  }
+  length_ = new_length;
+}
+
+
 template<typename T>
 class GrowableArray : public BaseGrowableArray<T, ValueObject> {
  public:
   GrowableArray(Isolate* isolate, intptr_t initial_capacity)
       : BaseGrowableArray<T, ValueObject>(
           initial_capacity, isolate->current_zone()) {}
   explicit GrowableArray(intptr_t initial_capacity)
       : BaseGrowableArray<T, ValueObject>(
           initial_capacity, Isolate::Current()->current_zone()) {}
   GrowableArray()
@@ skipping 13 matching lines @@
           initial_capacity,
           Isolate::Current()->current_zone()) {}
   ZoneGrowableArray() :
       BaseGrowableArray<T, ZoneAllocated>(
           Isolate::Current()->current_zone()) {}
 };
 
 }  // namespace dart
 
 #endif  // VM_GROWABLE_ARRAY_H_