Remove the url! plugin.

In rust-url 1.0 the `Url` struct is going to have private fields, and there
is no way to to create an aribitrary one without going through the parser.

The plugin never had a clear demonstrated performance benefit,
it was made mostly because it was possible and relatively easy at the time.

components/servo/Cargo.lock

@@ -32,7 +32,6 @@ dependencies = [
  "net_traits_tests 0.0.1",
  "offscreen_gl_context 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "plugin_compiletest 0.0.1",
- "plugin_tests 0.0.1",
  "profile 0.0.1",
  "profile_traits 0.0.1",
  "script 0.0.1",
@@ -1526,20 +1525,11 @@ dependencies = [
  "script 0.0.1",
 ]
 
-[[package]]
-name = "plugin_tests"
-version = "0.0.1"
-dependencies = [
- "plugins 0.0.1",
- "url 0.5.8 (registry+https://github.com/rust-lang/crates.io-index)",
-]
-
 [[package]]
 name = "plugins"
 version = "0.0.1"
 dependencies = [
  "tenacious 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)",
- "url 0.5.8 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]

components/servo/Cargo.toml

@@ -33,9 +33,6 @@ path = "../../tests/unit/net"
 [dev-dependencies.net_traits_tests]
 path = "../../tests/unit/net_traits"
 
-[dev-dependencies.plugin_tests]
-path = "../../tests/unit/plugin"
-
 [dev-dependencies.script_tests]
 path = "../../tests/unit/script"