Auto merge of #12468 - asajeffrey:constellation-remove-panic-channel, r=emilio

Removed panic channel, replaced by integrated logging and issue reporting

<!-- Please describe your changes on the following line: -->

Remove the previous ad hoc panic channel, replace it by an integrated logging and panicking mechanism, including crash reporting. All thread panics are now reported, not just content threads.

---
<!-- 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 #11838
- [X] These changes do not require tests because we don't test error reporting

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components/servo/Cargo.lock

@@ -2409,7 +2409,6 @@ name = "util"
 version = "0.0.1"
 dependencies = [
  "app_units 0.2.5 (registry+https://github.com/rust-lang/crates.io-index)",
- "backtrace 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "bitflags 0.7.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "euclid 0.7.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "getopts 0.2.14 (registry+https://github.com/rust-lang/crates.io-index)",

components/servo/main.rs

@@ -26,7 +26,6 @@ extern crate backtrace;
 extern crate glutin_app as app;
 #[cfg(target_os = "android")]
 extern crate libc;
-#[cfg(target_os = "android")]
 #[macro_use]
 extern crate log;
 // The Servo engine
@@ -38,8 +37,8 @@ extern crate sig;
 use servo::Browser;
 use servo::compositing::windowing::WindowEvent;
 use servo::util::opts::{self, ArgumentParsingResult};
-use servo::util::panicking::initiate_panic_hook;
 use servo::util::servo_version;
+use std::panic;
 use std::process;
 use std::rc::Rc;
 
@@ -94,7 +93,20 @@ fn main() {
         None
     };
 
-    initiate_panic_hook();
+    // TODO: once log-panics is released, this can be replaced by
+    // log_panics::init();
+    panic::set_hook(Box::new(|info| {
+        warn!("Panic hook called.");
+        let msg = match info.payload().downcast_ref::<&'static str>() {
+            Some(s) => *s,
+            None => match info.payload().downcast_ref::<String>() {
+                Some(s) => &**s,
+                None => "Box<Any>",
+            },
+        };
+        error!("{}", msg);
+    }));
+
     setup_logging();
 
     if let Some(token) = content_process_token {