Support symlinking to dart-sdk executables on Linux and Mac.

sdk/bin/pub_developer

Index: sdk/bin/pub_developer
diff --git a/sdk/bin/pub_developer b/sdk/bin/pub_developer
index be0510d990fbc78797d73fe57c7d153a5591215b..05adac9c3528afa2ce7323bce8f2c03902951741 100755
--- a/sdk/bin/pub_developer
+++ b/sdk/bin/pub_developer
@@ -7,9 +7,10 @@
 # structure.
 
 # Setting BIN_DIR this way is ugly, but is needed to handle the case where
-# dart-sdk/bin has been symlinked to. On MacOS, readlink doesn't work
-# with this case.
-BIN_DIR="$(cd "${0%/*}" ; pwd -P)"
+# dart-sdk/bin has been symlinked to. On MacOS, readlink -f doesn't work with
+# this case.
+SCRIPT=`readlink "$0" || echo "$0"`
+BIN_DIR="$(cd "${SCRIPT%/*}" ; pwd -P)"
 SDK_DIR="$(cd "${BIN_DIR}/.." ; pwd -P)"
 
 SNAPSHOT="$BIN_DIR/snapshots/pub.dart.snapshot"
@@ -40,4 +41,4 @@ else
   PUB="$SDK_DIR/lib/_internal/pub/bin/pub.dart"
 
   exec "$DART" "--checked" "--package-root=$PACKAGES_DIR" "$PUB" "$@"
-fi
+fi