CPU profiler: increase the max number of captured frames.

src/sampler.cc

Index: src/sampler.cc
diff --git a/src/sampler.cc b/src/sampler.cc
index aedf75f69abf9df0f68c13d98978579092caa17a..82fe27d861c7787cef8ba03a515e4defc6b140bf 100644
--- a/src/sampler.cc
+++ b/src/sampler.cc
@@ -596,7 +596,7 @@ DISABLE_ASAN void TickSample::Init(Isolate* isolate,
 
   SafeStackFrameIterator it(isolate, regs.fp, regs.sp, js_entry_sp);
   top_frame_type = it.top_frame_type();
-  int i = 0;
+  unsigned i = 0;
   while (!it.done() && i < TickSample::kMaxFramesCount) {
     stack[i++] = it.frame()->pc();
     it.Advance();