Generate cached_patches.dart using new Dartium swtich

tools/dartium/generate_patches.sh

 #!/usr/bin/env bash
 #
 
 set -x
 
 #   generate_patches.sh [systems]
 #
 # Convenience script to generate patches for JsInterop under Dartium.  Do not call from build steps or tests
 # - call fremontcutbuilder and dartdomgenerator instead. Do not add 'real'
 # functionality here - change the python code instead.
 #
 # I find it essential to generate all the systems so I know if I am breaking
 # other systems.  My habit is to run:
 #
 #   ./go.sh
-
+#
 # 1. After running go.sh libraries in sdk/lib may change.
 # 2. Build Dartium.
 # 3. Run this script and sdk/lib/js/dartium/cached_patches will be created.
 # 4. Rebuild Dartium.
 # 5. Commit files in sdk/lib
+#
+# NOTE: If the Dart files generated from the IDLs may cause major changes which
+#       could cause the patch files to fail (missing classes, etc).  If this
+#       happens delete the contents of the sdk/lib/js/dartium/cached_patches.dart
+#       build Dartium, run this script and build Dartium again with the newly
+#       generated patches. 
 
 LOCATION_DARTIUM="../../../out/Release"
 DARTIUM="$LOCATION_DARTIUM"
 
 DART_APP_LOCATION="file://"$PWD"/generate_app/generate_cached_patches.html"
-DARTIUM_ARGS=" --user-data-dir=out --disable-web-security --no-sandbox --enable-logging=stderr"
+DARTIUM_ARGS=" --user-data-dir=out --disable-web-security --no-sandbox --enable-blink-features=dartGenCachedPatches"
 CACHED_PATCHES_FILE=""$PWD"/../../sdk/lib/js/dartium/cached_patches.dart"
 
 if [[ "$1" != "" ]] ; then
   DARTIM="$1"
 fi
 
-cmd=""$DARTIUM"/chrome "$DARTIUM_ARGS" "$DART_APP_LOCATION" 3>&1 1>&2- 2>&3 | \
+cmd=""$DARTIUM"/chrome "$DARTIUM_ARGS" "$DART_APP_LOCATION" |
   (sed -n '/START_OF_CACHED_PATCHES/,/END_OF_CACHED_PATCHES/p') > "$CACHED_PATCHES_FILE""
 
 reset && eval "${cmd}"