Add constant info to the dart2js_info model

README.md

 # Dart2js Info
 
 This package contains libraries and tools you can use to process `.info.json`
 files, which are produced when running dart2js with `--dump-info`.
 
 The `.info.json` files contain data about each element included in
 the output of your program. The data includes information such as:
 
   * the size that each function adds to the `.dart.js` output,
   * dependencies between functions,
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   specification implicitly defines several groups, one per observed name.
 
   * `cluster` (optional): a clustering index for how data is shown in a table.
   Groups with higher cluster indices are shown later in the table after a
   dividing line. If missing, the cluster index defaults to 0.
 
 Here is an example configuration, with comments about what each entry does:
 
 ```yaml
 groups:
-# This group shows the total size of all libraries together, it is shown in
-# cluster #3, which happens to be the last cluster in this example:
-- name: "Total (excludes preambles, statics & consts)"
-  regexp: ".*"
-  cluster: 3
-
 # This group shows the total size for all libraries that were loaded from
-# file:// urls:
-- { name: "Loose files", regexp: "file://.*", cluster: 2}
+# file:// urls, it is shown in cluster #2, which happens to be the last
+# cluster in this example before the totals are shown:
+- name: "Loose files"
+  regexp: "file://.*"
+  cluster: 2
 
 # This group shows the total size of all code loaded from packages:
 - { name: "All packages", regexp: "package:.*", cluster: 2}
 
 # This group shows the total size of all code loaded from core libraries:
 - { name: "Core libs", regexp: "dart:.*", cluster: 2}
 
 # This group shows the total size of all libraries in a single package. Here
 # we omitted the `name` entry, instead we extract it from the regexp
 # directly.  In this case, the name will be the package-name portion of the
 # package-url (determined by group(1) of the regexp).
 - { regexp: "package:([^/]*)", cluster: 1}
 
 # The next two groups match the entire library url as the name of the group.
 - regexp: "package:.*"
 - regexp: "dart:.*"
 
 # If your code lives under /my/project/dir, this will match any file loaded
 from a file:// url, and we use as a name the relative path to it.
 - regexp: "file:///my/project/dir/(.*)"
 ```
 
+Regardless of the grouping configuration, the tool will display the total code
+size attributed of all libraries, constants, and the program size.
+
+**Note**: eventually you should expect all numbers to add up to the program
+size. Currently dart2js's `--dump-info` is not complete, so numbers for
+bootstraping code and lazy static initializers are missing.
+
 ### Function size analysis tool
 
 This command-line tool presents how much each function contributes to the total
 code of your application.  We use dependency information to compute dominance
 and reachability data as well.
 
 When you run:
 ```bash
 pub global activate dart2js_info # only needed once
 pub global run dart2js_info:function_size_analysis out.js.info.json
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 bugs at the [issue tracker][tracker].
 
 [repo]: https://github.com/dart-lang/dart2js_info/
 [tracker]: https://github.com/dart-lang/dart2js_info/issues
 [code_deps]: https://github.com/dart-lang/dart2js_info/blob/master/bin/code_deps.dart
 [lib_split]: https://github.com/dart-lang/dart2js_info/blob/master/bin/library_size_split.dart
 [coverage]: https://github.com/dart-lang/dart2js_info/blob/master/bin/coverage_log_server.dart
 [live]: https://github.com/dart-lang/dart2js_info/blob/master/bin/live_code_size_analysis.dart
 [function_analysis]: https://github.com/dart-lang/dart2js_info/blob/master/bin/function_size_analysis.dart
 [AllInfo]: http://dart-lang.github.io/dart2js_info/doc/api/dart2js_info.info/AllInfo-class.html