[debug] refactor code coverage to use enum for mode.

src/runtime/runtime-debug.cc

Index: src/runtime/runtime-debug.cc
diff --git a/src/runtime/runtime-debug.cc b/src/runtime/runtime-debug.cc
index 0d555e60320a9cd1d341148ca8ddf16de69aa367..3eeb199204f62b4cb765fc2b4bf8462cf64cab7d 100644
--- a/src/runtime/runtime-debug.cc
+++ b/src/runtime/runtime-debug.cc
@@ -1945,7 +1945,8 @@ RUNTIME_FUNCTION(Runtime_DebugCollectCoverage) {
 RUNTIME_FUNCTION(Runtime_DebugTogglePreciseCoverage) {
   SealHandleScope shs(isolate);
   CONVERT_BOOLEAN_ARG_CHECKED(enable, 0);
-  Coverage::TogglePrecise(isolate, enable);
+  Coverage::SelectMode(isolate, enable ? debug::Coverage::kPreciseCount
+                                       : debug::Coverage::kBestEffort);
   return isolate->heap()->undefined_value();
 }