Use a heap for the released handle list.

src/libANGLE/HandleAllocator.cpp

@@ -49,9 +49,10 @@ GLuint HandleAllocator::allocate()
 {
     ASSERT(!mUnallocatedList.empty() || !mReleasedList.empty());
 
-    // Allocate from released list, constant time.
+    // Allocate from released list, logarithmic time for pop_heap.
     if (!mReleasedList.empty())
     {
+        std::pop_heap(mReleasedList.begin(), mReleasedList.end());
         GLuint reusedHandle = mReleasedList.back();
         mReleasedList.pop_back();
         return reusedHandle;
@@ -77,8 +78,9 @@ GLuint HandleAllocator::allocate()
 
 void HandleAllocator::release(GLuint handle)
 {
-    // Add to released list, constant time.
+    // Add to released list, logarithmic time for push_heap.
     mReleasedList.push_back(handle);
+    std::push_heap(mReleasedList.begin(), mReleasedList.end());
 }
 
 void HandleAllocator::reserve(GLuint handle)

src/libANGLE/HandleAllocator.h

@@ -14,8 +14,6 @@
 
 #include "angle_gl.h"
 
-#include <stack>
-
 namespace gl
 {
 
@@ -55,7 +53,7 @@ class HandleAllocator final : angle::NonCopyable
 
     // The freelist consists of never-allocated handles, stored
     // as ranges, and handles that were previously allocated and
-    // released, stored in a stack.
+    // released, stored in a heap.
     std::vector<HandleRange> mUnallocatedList;
     std::vector<GLuint> mReleasedList;
 };