Switch SetupIsolateForProfiling to use calloc instead of new []

runtime/vm/profiler.cc

Index: runtime/vm/profiler.cc
diff --git a/runtime/vm/profiler.cc b/runtime/vm/profiler.cc
index 90d5a46ac786653e7b944a93b757e9aeb6c1a12c..d3b25f2daa5b6b6c1dc78b650add88eec76f455d 100644
--- a/runtime/vm/profiler.cc
+++ b/runtime/vm/profiler.cc
@@ -579,14 +579,17 @@ SampleBuffer::SampleBuffer(intptr_t capacity) {
   start_ = 0;
   end_ = 0;
   capacity_ = capacity;
-  samples_ = new Sample[capacity];
+  samples_ = reinterpret_cast<Sample*>(calloc(capacity, sizeof(Sample)));
 }
 
 
 SampleBuffer::~SampleBuffer() {
   if (samples_ != NULL) {
-    delete[] samples_;
+    free(samples_);
     samples_ = NULL;
+    start_ = 0;
+    end_ = 0;
+    capacity_ = 0;
   }
 }