Auto merge of #11462 - Manishearth:devtools-fixes, r=Ms2ger

devtools: fix segfault, remove println

This fixes the segfault from #11457 by adding an autocompartment.

It also removes the print statements which clog the command line and replaces
them with `debug!()`

---
<!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `__` with appropriate data: -->
- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [x] These changes fix #11457 (github issue number if applicable).

<!-- Either: -->
- [ ] There are tests for these changes OR
- [x] These changes do not require tests because we don't have full-server
  devtools tests

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ports/cef/Cargo.lock

@@ -441,6 +441,7 @@ dependencies = [
  "devtools_traits 0.0.1",
  "hyper 0.9.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "ipc-channel 0.2.2 (git+https://github.com/servo/ipc-channel)",
+ "log 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "msg 0.0.1",
  "plugins 0.0.1",
  "serde 0.7.5 (registry+https://github.com/rust-lang/crates.io-index)",

ports/gonk/Cargo.lock

@@ -443,6 +443,7 @@ dependencies = [
  "devtools_traits 0.0.1",
  "hyper 0.9.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "ipc-channel 0.2.2 (git+https://github.com/servo/ipc-channel)",
+ "log 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "msg 0.0.1",
  "plugins 0.0.1",
  "serde 0.7.5 (registry+https://github.com/rust-lang/crates.io-index)",