Create a top-level "third_party" directory

This directory now contains third_party software that is vendored into
the Servo source tree. The idea is that it would eventually hold
webrender and other crates from mozilla-central as well with a standard
patch management approach for each.

third_party/WebIDL/tests/test_undefined.py

@@ -0,0 +1,246 @@
+import WebIDL
+
+
+def WebIDLTest(parser, harness):
+    try:
+        parser.parse(
+            """
+            dictionary Dict {
+              undefined undefinedMember;
+              double bar;
+            };
+            """
+        )
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "undefined must not be used as the type of a dictionary member")
+
+    parser = parser.reset()
+    threw = False
+
+    try:
+        parser.parse(
+            """
+            dictionary Dict {
+              (undefined or double) undefinedMemberOfUnionInDict;
+            };
+            """
+        )
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(
+        threw,
+        "undefined must not be used as the type of a dictionary member, "
+        "whether directly or in a union",
+    )
+
+    parser = parser.reset()
+    threw = False
+
+    try:
+        parser.parse(
+            """
+            interface Foo {
+              double bar(undefined foo);
+            };
+            """
+        )
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(
+        threw,
+        "undefined must not be used as the type of an argument in any "
+        "circumstance (so not as the argument of a regular operation)",
+    )
+
+    parser = parser.reset()
+    threw = False
+
+    try:
+        parser.parse(
+            """
+            interface Foo {
+              getter double(undefined name);
+            };
+            """
+        )
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(
+        threw,
+        "undefined must not be used as the type of an argument in any "
+        "circumstance (so not as the argument of a getter)",
+    )
+
+    parser = parser.reset()
+    threw = False
+
+    try:
+        parser.parse(
+            """
+            interface Foo {
+              setter undefined(DOMString name, undefined value);
+            };
+            """
+        )
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(
+        threw,
+        "undefined must not be used as the type of an argument in any "
+        "circumstance (so not as the argument of a setter)",
+    )
+
+    parser = parser.reset()
+    threw = False
+
+    try:
+        parser.parse(
+            """
+            interface Foo {
+              deleter undefined (undefined name);
+            };
+            """
+        )
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(
+        threw,
+        "undefined must not be used as the type of an argument in any "
+        "circumstance (so not as the argument of a deleter)",
+    )
+
+    parser = parser.reset()
+    threw = False
+
+    try:
+        parser.parse(
+            """
+            interface Foo {
+              constructor (undefined foo);
+            };
+            """
+        )
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(
+        threw,
+        "undefined must not be used as the type of an argument in any "
+        "circumstance (so not as the argument of a constructor)",
+    )
+
+    parser = parser.reset()
+    threw = False
+
+    try:
+        parser.parse(
+            """
+            callback Callback = undefined (undefined foo);
+            """
+        )
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(
+        threw,
+        "undefined must not be used as the type of an argument in any "
+        "circumstance (so not as the argument of a callback)",
+    )
+
+    parser = parser.reset()
+    threw = False
+
+    try:
+        parser.parse(
+            """
+            interface Foo {
+              async iterable(undefined name);
+            };
+            """
+        )
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(
+        threw,
+        "undefined must not be used as the type of an argument in any "
+        "circumstance (so not as the argument of an async iterable "
+        "iterator)",
+    )
+
+    parser = parser.reset()
+    threw = False
+
+    try:
+        parser.parse(
+            """
+            interface Foo {
+              static double bar(undefined foo);
+            };
+            """
+        )
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(
+        threw,
+        "undefined must not be used as the type of an argument in any "
+        "circumstance (so not as the argument of a static operation)",
+    )
+
+    parser = parser.reset()
+    threw = False
+
+    try:
+        parser.parse(
+            """
+            interface Foo {
+              const undefined FOO = undefined;
+            };
+            """
+        )
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(
+        threw,
+        "undefined is not a valid type for a constant",
+    )
+
+    parser = parser.reset()
+    threw = False
+
+    try:
+        parser.parse(
+            """
+            interface Foo {
+              const any FOO = undefined;
+            };
+            """
+        )
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(
+        threw,
+        "undefined is not a valid value for a constant",
+    )