Remove Chromium's custom closure runner.

third_party/closure_compiler/roll_closure_compiler

Index: third_party/closure_compiler/roll_closure_compiler
diff --git a/third_party/closure_compiler/roll_closure_compiler b/third_party/closure_compiler/roll_closure_compiler
index 680275eb13aa10f3f2c0afc2335a4cde2ff2c180..ca11c79fb1dbc93a909dd9d8a9475b652579912a 100755
--- a/third_party/closure_compiler/roll_closure_compiler
+++ b/third_party/closure_compiler/roll_closure_compiler
@@ -5,6 +5,11 @@
 #
 # Download the newest version of Closure Compiler, build it and put into Chrome
 # source tree. Also update externs/chrome_extensions.js.
+#
+# TODO(dbeam): we don't really need to build the compiler any more. We used to
+# need to because we built a custom runner. We could probably just curl
+# https://dl.google.com/closure-compiler/compiler-latest.zip and unzip. And get
+# the externs from rawgit.com.
 
 java -version 2>&1 | head -1 | egrep -q '\b1\.7'
 if [[ $? -ne 0 ]]; then
@@ -67,19 +72,9 @@ if [[ "$?" -ne 0 ]]; then
   exit 1
 fi
 
-# TODO(dbeam): this .jar seems to be a bit bigger than the jar previously built
-# by ant. I tried many other jars in target/, but none of them were able to
-# build the runner.jar without issue.
+# TODO(dbeam): the Maven-built jar seems a little bigger than the ant version.
 cp target/closure-compiler-1.0-SNAPSHOT.jar "${SCRIPT_DIR}/compiler/compiler.jar"
 
-echo "Re-building runner.jar"
-"${SCRIPT_DIR}/runner/build_runner_jar.py"
-if [[ "$?" -ne 0 ]]; then
-  echo "Failed to build runner.jar, roll unsuccessful"
-  cleanup
-  exit 1
-fi
-
 readonly WARNING="$(cat <<EOT
 //    SSSSSSSSSSSSSSS TTTTTTTTTTTTTTTTTTTTTTT     OOOOOOOOO     PPPPPPPPPPPPPPPPP
 //  SS:::::::::::::::ST:::::::::::::::::::::T   OO:::::::::OO   P::::::::::::::::P