test_runner: make file path relative properly

lib/internal/test_runner/reporter/lcov.js

@@ -1,10 +1,6 @@
 'use strict';
 
-const {
-  StringPrototypeReplace,
-} = primordials;
-
-
+const { relative } = require('path');
 const Transform = require('internal/streams/transform');
 
 // This reporter is based on the LCOV format, as described here:
@@ -37,7 +33,7 @@ class LcovReporter extends Transform {
         // For each source file referenced in the .da file, there is a section
         // containing filename and coverage data:
         // ## SF:\<path to the source file\>
-        lcov += `SF:${StringPrototypeReplace(file.path, `${workingDirectory}/`, '')}\n`;
+        lcov += `SF:${relative(workingDirectory, file.path)}\n`;
 
         // Following is a list of line numbers for each function name found in
         // the source file: