servo: Merge #7813 - Run all unit tests with just one Cargo command (…

…from servo:parallel-unit-tests); r=mbrubeck

Upgrade Cargo to get rust-lang/cargo#1828, and use it for unit tests. This allows Cargo to get some more parallelism when compiling the test crates’ dependencies.

`touch components/util/lib.rs && mach test-unit` on my machine goes from 149 seconds to 124.

Source-Repo: https://github.com/servo/servo
Source-Revision: ba2714f4f607da77bd7200f88cfa16c1d10da9cd

UltraBlame original commit: a747ff057fac88586b57a543cf00052e24c93afe

servo/cargo-nightly-build

@@ -1,5 +1,5 @@
 2015
 -
-08
+10
 -
-20
+01

servo/python/servo/testing_commands.py

@@ -1469,26 +1469,27 @@
 )
 )
 
-for
-crate
-in
-packages
-:
-
-result
+args
 =
-subprocess
-.
-call
-(
-
 [
 "
 cargo
 "
 "
 test
 "
+]
+
+for
+crate
+in
+packages
+:
+
+args
++
+=
+[
 "
 -
 p
@@ -1500,9 +1501,19 @@
 %
 crate
 ]
+
+args
 +
+=
 test_patterns
-
+
+result
+=
+subprocess
+.
+call
+(
+args
 env
 =
 self
@@ -1518,14 +1529,14 @@
 (
 )
 )
-            
+
 if
 result
 !
 =
 0
 :
-                
+
 return
 result