Speed up two tests by skipping slow asserts

pending a better approach.

Bug: v8:8516
Change-Id: Ic107184b46c85ae5724619cc82c99686aee7edb9
Reviewed-on: https://chromium-review.googlesource.com/c/1352794Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Jakob Kummerow <jkummerow@chromium.org>
Cr-Commit-Position: refs/heads/master@{#57893}

test/cctest/test-heap-profiler.cc

@@ -2396,6 +2396,11 @@ TEST(MapHasDescriptorsAndTransitions) {
 
 
 TEST(ManyLocalsInSharedContext) {
+  // This test gets very slow with slow asserts (18 minutes instead of 1:30,
+  // as of November 2018).
+#ifdef ENABLE_SLOW_DCHECKS
+  i::FLAG_enable_slow_asserts = false;
+#endif
   LocalContext env;
   v8::HandleScope scope(env->GetIsolate());
   v8::HeapProfiler* heap_profiler = env->GetIsolate()->GetHeapProfiler();

test/mjsunit/regress/regress-748069.js

@@ -2,6 +2,9 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// This test gets very slow with slow asserts.
+// Flags: --noenable-slow-asserts
+
 try {
   var a = 'a'.repeat(1 << 28);
 } catch (e) {