[modules] Add basic path normalization to d8's module loader

test/mjsunit/modules-relative-path.js

Index: test/mjsunit/modules-relative-path.js
diff --git a/test/mjsunit/modules-fail-star-exports-conflict.js b/test/mjsunit/modules-relative-path.js
similarity index 54%
copy from test/mjsunit/modules-fail-star-exports-conflict.js
copy to test/mjsunit/modules-relative-path.js
index 6e2b2193422e770ee4f92f2a8dc0affa3f2d62dc..7e6a37ac1c5ab18f05256aac2cf8eec8b2cd6d14 100644
--- a/test/mjsunit/modules-fail-star-exports-conflict.js
+++ b/test/mjsunit/modules-relative-path.js
@@ -4,7 +4,11 @@
 //
 // MODULE
 
-export * from "modules-skip-star-exports-conflict.js";
-export * from "modules-skip-6.js";
+import {x as y} from "./modules-relative-path.js";
+export let x = 0;
 
-import {a} from "modules-fail-star-exports-conflict.js";
+assertEquals(0, x);
+assertEquals(x, y);
+x++;
+assertEquals(1, x);
+assertEquals(x, y);