Servo Greeter

Heads up! This PR modifies the following files: * @asajeffrey: components/script/dom/webidls/IDBTransaction.webidl, components/script/dom/idbrequest.rs, components/script/dom/mod.rs, components/script/dom/window.rs, components/script/dom/idbobjectstore.rs and 14 more * @kichjang: components/script/dom/webidls/IDBTransaction.webidl, components/net/lib.rs, components/script/dom/idbrequest.rs, components/script/dom/mod.rs, components/net/indexeddb/mod.rs and 24 more

**Warning** * These commits modify **unsafe code**. Please review it carefully! * These commits modify net and script code, but no tests are modified. Please consider adding a test!

**Warning** * These commits modify **unsafe code**. Please review it carefully!

**Warning** * These commits modify **unsafe code**. Please review it carefully!

**Warning** * These commits modify **unsafe code**. Please review it carefully!

Thanks for the pull request, and welcome! The Servo team is excited to review your changes, and you should hear from @simonsapin (or someone else) soon.

Heads up! This PR modifies the following files: * @wafflespeanut: python/servo/bootstrap_commands.py, python/servo/bootstrap.py

Heads up! This PR modifies the following files: * @asajeffrey: components/script/dom/bindings/codegen/CodegenRust.py, components/script/dom/bindings/proxyhandler.rs, components/script/dom/location.rs * @kichjang: components/script/dom/bindings/codegen/CodegenRust.py, components/script/dom/bindings/proxyhandler.rs, components/script/dom/location.rs

**Warning** * These commits modify **unsafe code**. Please review it carefully! * These commits modify script code, but no tests are modified. Please consider adding a test!

Hi! If you have any questions regarding this issue, feel free to make a comment here, or ask it in the `#servo` channel in [IRC](https://wiki.mozilla.org/IRC). If you intend to work...