1 files changed, 27 insertions, 0 deletions
diff --git a/js/src/jit-test/tests/basic/bug920484.js b/js/src/jit-test/tests/basic/bug920484.js
new file mode 100644
index 0000000000..34c1ff6a76
--- /dev/null
+++ b/js/src/jit-test/tests/basic/bug920484.js
@@ -0,0 +1,27 @@
+load(libdir + "asserts.js");
+
+// Add an invalid "localeMatcher" option to Object.prototype, the exact value does not matter,
+// any value except "best fit" or "lookup" is okay.
+Object.prototype.localeMatcher = "invalid matcher option";
+
+// The Intl API may not be available in the testing environment.
+if (this.hasOwnProperty("Intl")) {
+    // Intl constructors still work perfectly fine. The default options object doesn't inherit
+    // from Object.prototype and the invalid "localeMatcher" value from Object.prototype isn't
+    // consulted.
+    new Intl.Collator().compare("a", "b");
+    new Intl.NumberFormat().format(10);
+    new Intl.DateTimeFormat().format(new Date);
+
+    // If an explicit "localeMatcher" option is given, the default from Object.prototype is ignored.
+    new Intl.Collator(void 0, {localeMatcher: "lookup"}).compare("a", "b");
+    new Intl.NumberFormat(void 0, {localeMatcher: "lookup"}).format(10);
+    new Intl.DateTimeFormat(void 0, {localeMatcher: "lookup"}).format(new Date);
+
+    delete Object.prototype.localeMatcher;
+
+    // After removing the default option from Object.prototype, everything still works as expected.
+    new Intl.Collator().compare("a", "b");
+    new Intl.NumberFormat().format(10);
+    new Intl.DateTimeFormat().format(new Date);
+}