Auto merge of #13063 - larsbergstrom:remove_git_info, r=metajack

Remove static usage at compile-time of GIT_INFO to enable builds outs…

r? @metajack

The issue here is that if we build Servo from a expanded copy of the sources w/o a git repository present in-tree, this will fail. Further, we can't switch to `option_env` with an `unwrap_or` because `concat!` expects string literals.

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components/script/dom/htmliframeelement.rs

@@ -355,7 +355,7 @@ unsafe fn build_mozbrowser_event_detail(event: MozBrowserEvent,
                 type_: Some(DOMString::from(error_type.name())),
                 description: Some(DOMString::from(description)),
                 report: Some(DOMString::from(report)),
-                version: Some(DOMString::from_string(servo_version().into())),
+                version: Some(DOMString::from_string(servo_version())),
             }.to_jsval(cx, rval);
         },
         MozBrowserEvent::SecurityChange(https_state) => {