[debug] do not report unnecessary coverage data.

src/debug/debug-coverage.h

Index: src/debug/debug-coverage.h
diff --git a/src/debug/debug-coverage.h b/src/debug/debug-coverage.h
index f37b8f37440fe7697054ecca2c8655bc8c598ed0..5a4ac15569ceb950359f6cf4d271cb1203a34716 100644
--- a/src/debug/debug-coverage.h
+++ b/src/debug/debug-coverage.h
@@ -27,7 +27,7 @@ struct CoverageFunction {
 
 struct CoverageScript {
   // Initialize top-level function in case it has been garbage-collected.
-  CoverageScript(Isolate* isolate, Handle<Script> s) : script(s) {}
+  explicit CoverageScript(Handle<Script> s) : script(s) {}
   Handle<Script> script;
   // Functions are sorted by start position, from outer to inner function.
   std::vector<CoverageFunction> functions;