Roll Observatory packages and add a roll script

charted/lib/core/utils/namespace.dart

-//
-// Copyright 2014 Google Inc. All rights reserved.
-//
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file or at
-// https://developers.google.com/open-source/licenses/bsd
-//
-
-part of charted.core.utils;
-
-/// Basic namespace handing for Charted - includes utilities to
-/// parse the namespace prefixes and to create DOM elements using a
-/// namespace.
-class Namespace {
-  /// Supported namespace prefixes mapped to their URIs.
-  static const Map<String,String> NS_PREFIXES = const {
-    "svg": "http://www.w3.org/2000/svg",
-    "xhtml": "http://www.w3.org/1999/xhtml",
-    "xlink": "http://www.w3.org/1999/xlink",
-    "xml": "http://www.w3.org/XML/1998/namespace",
-    "xmlns": "http://www.w3.org/2000/xmlns/"
-  };
-
-  /// Create an element from [tag]. If tag is prefixed with a
-  /// supported namespace prefix, the created element will
-  /// have the namespaceUri set to the correct URI.
-  static Element createChildElement(String tag, Element parent) {
-    var separatorIndex = tag.indexOf(':');
-    if (separatorIndex == -1 && parent != null) {
-      return parent.ownerDocument.createElementNS(parent.namespaceUri, tag);
-    }
-    Namespace parsed = new Namespace._internal(tag, separatorIndex);
-    return parsed.namespaceUri == null ?
-        parent.ownerDocument.createElementNS(parent.namespaceUri, tag) :
-        parent.ownerDocument.createElementNS(parsed.namespaceUri,
-            parsed.localName);
-  }
-
-  /// Local part of the Element's tag name.
-  String localName;
-
-  /// Name space URI for the selected namespace.
-  String namespaceUri;
-
-  /// Parses a tag for namespace prefix and local name.
-  /// If a known namespace prefix is found, sets the namespaceUri property
-  /// to the URI of the namespace.
-  factory Namespace(String tagName) =>
-      new Namespace._internal(tagName, tagName.indexOf(':'));
-
-  /// Utility for use by createChildElement and factory constructor.
-  Namespace._internal(String tagName, int separatorIdx) {
-    String prefix = tagName;
-    if (separatorIdx >= 0) {
-      prefix = tagName.substring(0, separatorIdx);
-      localName = tagName.substring(separatorIdx + 1);
-    }
-
-    if (NS_PREFIXES.containsKey(prefix)) {
-      namespaceUri = NS_PREFIXES[prefix];
-    } else {
-      localName = tagName;
-    }
-  }
-}