Make it possible to symlink to dartdoc and pub in the SDK.

sdk/bin/pub

 #!/bin/bash
 # Copyright (c) 2013, 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
+  file="$1"
+  while [ -h "$file" ]; do
     # On Mac OS, readlink -f doesn't work.
-    1="$(readlink "$1")"
+    file="$(readlink "$file")"
   done
-  echo "$1"
+  echo "$(cd "$(dirname $file)"; pwd -P)/$(basename "$file")"
 }
 
-# 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)"
+# Unlike $0, $BASH_SOURCE points to the absolute path of this file. Follow
+# symlinks to handle the case where dart-sdk/bin or dart-sdk/bin/pub have been
+# linked to.
+BIN_DIR="$(dirname "$(follow_links "$BASH_SOURCE")")"
+SDK_DIR="$(dirname "$BIN_DIR")"
 
 DART="$BIN_DIR/dart"
 
 SNAPSHOT="$BIN_DIR/snapshots/pub.dart.snapshot"
 
 if test -f "$SNAPSHOT"; then
   # We are running the snapshot in the built SDK.
   exec "$DART" "--checked" "$SNAPSHOT" "$@"
 else
   # We are running pub from source in the development repo.
   if [ -z "$DART_CONFIGURATION" ];
   then
     DART_CONFIGURATION="ReleaseIA32"
   fi
 
   if [[ `uname` == 'Darwin' ]];
   then
     PACKAGES_DIR="$SDK_DIR"/../xcodebuild/$DART_CONFIGURATION/packages/
   else
     PACKAGES_DIR="$SDK_DIR"/../out/$DART_CONFIGURATION/packages/
   fi
 
   PUB="$SDK_DIR/lib/_internal/pub/bin/pub.dart"
 
   exec "$DART" "--checked" "--package-root=$PACKAGES_DIR" "$PUB" "$@"
 fi