Switch to using pub build instead of custom build_.dart script

runtime/bin/vmservice/client/deploy.sh

+#!/bin/sh
+
+# This script copies the build outputs produced by `pub build` to
+# the deployed directory.
+
+if [ ! -d "build" ]; then
+  echo "Please run pub build first"
+  exit
+fi
+
+if [ ! -d "deployed" ]; then
+  echo "Run this script from the client directory"
+  exit
+fi
+
+EXCLUDE="--exclude bootstrap_css"
+EXCLUDE="$EXCLUDE --exclude *.scriptUrls"
+EXCLUDE="$EXCLUDE --exclude *.precompiled.js"
+EXCLUDE="$EXCLUDE --exclude main.*"
+
+rsync -av --progress build/web/ deployed/web/ $EXCLUDE