[cctest] Disable --enable-slow-asserts for FuzzAssemble* tests.

The FuzzAssemble* tests rely on two CSA functions which are relatively big. And
with the --enable-slow-asserts flag they get so big that the register
allocator's memory consumption becomes a problem. Let's just override this flag.

Bug: v8:7819, v8:6848, v8:7842
Change-Id: I95db59b9c788aa665d04339892b2e0b5d92d9a89
Reviewed-on: https://chromium-review.googlesource.com/1093315Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Pierre Langlois <pierre.langlois@arm.com>
Cr-Commit-Position: refs/heads/master@{#53779}

test/cctest/compiler/test-code-generator.cc

@@ -673,8 +673,18 @@ class TestEnvironment : public HandleAndZoneScope {
     Handle<FixedArray> state_out = main_isolate()->factory()->NewFixedArray(
         static_cast<int>(layout_.size()));
     {
+#ifdef ENABLE_SLOW_DCHECKS
+      // The "setup" and "teardown" functions are relatively big, and with
+      // runtime assertions enabled they get so big that memory during register
+      // allocation becomes a problem. Temporarily disable such assertions.
+      bool old_enable_slow_asserts = FLAG_enable_slow_asserts;
+      FLAG_enable_slow_asserts = false;
+#endif
       Handle<Code> setup =
           BuildSetupFunction(main_isolate(), test_descriptor_, layout_);
+#ifdef ENABLE_SLOW_DCHECKS
+      FLAG_enable_slow_asserts = old_enable_slow_asserts;
+#endif
       // FunctionTester maintains its own HandleScope which means that its
       // return value will be freed along with it. Copy the result into
       // state_out.