Add a snapshot for docgen and use it in the build

sdk/bin/docgen

Index: sdk/bin/docgen
diff --git a/sdk/bin/dartdoc b/sdk/bin/docgen
similarity index 58%
copy from sdk/bin/dartdoc
copy to sdk/bin/docgen
index 45ba5125b3ad43f0a18139b0febcf246050a05e1..b6822fa525416efc6ebc43522a27049ec364c0ae 100755
--- a/sdk/bin/dartdoc
+++ b/sdk/bin/docgen
@@ -1,5 +1,5 @@
 #!/bin/bash
-# Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
+# Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 # for details. All rights reserved. Use of this source code is governed by a
 # BSD-style license that can be found in the LICENSE file.
 
@@ -18,15 +18,6 @@ PROG_NAME="$(follow_links "$BASH_SOURCE")"
 # Handle the case where dart-sdk/bin has been symlinked to.
 BIN_DIR="$(cd "${PROG_NAME%/*}" ; pwd -P)"
 
-unset COLORS
-if test -t 1; then
-  # Stdout is a terminal.
-  if test 8 -le `tput colors`; then
-    # Stdout has at least 8 colors, so enable colors.
-    COLORS="--enable-diagnostic-colors"
-  fi
-fi
-
 unset SNAPSHOT
 
 SNAPSHOT="$BIN_DIR/snapshots/utils_wrapper.dart.snapshot"
@@ -34,11 +25,10 @@ SNAPSHOT="$BIN_DIR/snapshots/utils_wrapper.dart.snapshot"
 if test -f $SNAPSHOT; then
   # TODO(ahe): Remove the following line when we are relatively sure it works.
   echo Using snapshot $SNAPSHOT 1>&2
-  exec "$BIN_DIR"/dart --heap_growth_rate=32 \
-      "--package-root=$BIN_DIR/../packages/" $SNAPSHOT dartdoc $COLORS \
-      "--package-root=$BIN_DIR/../packages/" "--library-root=$BIN_DIR/.." "$@"
+  exec "$BIN_DIR"/dart \
+      "--package-root=$BIN_DIR/../packages/" $SNAPSHOT docgen "$@"
 else
-  exec "$BIN_DIR"/dart --heap_growth_rate=32 \
+  exec "$BIN_DIR"/dart \
       "--package-root=$BIN_DIR/../packages/" \
-      "$BIN_DIR/../lib/_internal/dartdoc/bin/dartdoc.dart" $COLORS "$@"
+      "$BIN_DIR/../pkg/docgen/bin/docgen.dart" "$@"
 fi