Correct snapshot location and fix a dependency problem.

dart/sdk/bin/dart2js

 #!/bin/bash
 # Copyright (c) 2012, 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.
 
 function follow_links() {
   while [ -h "$1" ]; do
     # On Mac OS, readlink -f doesn't work.
     1="$(readlink "$1")"
   done
   echo "$1"
 }
 
 # Unlike $0, $BASH_SOURCE points to the absolute path of this file.
 PROG_NAME="$(follow_links "$BASH_SOURCE")"
 
 # Handle the case where dart-sdk/bin has been symlinked to.
 BIN_DIR="$(follow_links "$(cd "${PROG_NAME%/*}" ; pwd -P)")"
 
 SDK_DIR="$(cd "${BIN_DIR}/.." ; pwd -P)"
 
 DART2JS="$SDK_DIR/lib/_internal/compiler/implementation/dart2js.dart"
+
 DART="$BIN_DIR/dart"
 
+SNAPSHOT="${DART2JS}.snapshot"
+
 unset EXTRA_OPTIONS
 declare -a EXTRA_OPTIONS
 
 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.
     EXTRA_OPTIONS[${#EXTRA_OPTIONS[@]}]='--enable-diagnostic-colors'
   fi
 fi
 
 unset EXTRA_VM_OPTIONS
 declare -a EXTRA_VM_OPTIONS
 
-SNAPSHOT="$SDK_DIR/_internal/compiler/implementation/dart2js.dart.snapshot"
 if test -f "$SNAPSHOT"; then
   # TODO(ahe): Remove the following line when we are relatively sure it works.
   echo Using snapshot "$SNAPSHOT" 1>&2
   EXTRA_VM_OPTIONS[${#EXTRA_VM_OPTIONS[@]}]="--use_script_snapshot=$SNAPSHOT"
 fi
 
 # Tell the VM to grow the heap more aggressively. This should only
 # be necessary temporarily until the VM is better at detecting how
 # applications use memory.
 # TODO(ahe): Remove this option (http://dartbug.com/6495).
 EXTRA_VM_OPTIONS[${#EXTRA_VM_OPTIONS[@]}]='--heap_growth_rate=512'
 
 # Tell the VM to don't bother inlining methods. So far inlining isn't
 # paying off but the VM team is working on fixing that.
 # TODO(ahe): Remove this option (http://dartbug.com/6495).
 EXTRA_VM_OPTIONS[${#EXTRA_VM_OPTIONS[@]}]='--no_use_inlining'
 
 case $0 in
   *_developer)
     EXTRA_VM_OPTIONS[${#EXTRA_VM_OPTIONS[@]}]='--checked'
     ;;
 esac
 
 exec "$DART" "${EXTRA_VM_OPTIONS[@]}" "$DART2JS" "${EXTRA_OPTIONS[@]}" "$@"