update pubspec/changelog in prep for merge into master (#48)

CHANGELOG.md

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 659274f..bc7c9ef 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,4 +1,4 @@
-## 1.0.0-dev
+## 0.11.0-nullsafety
 
 * Migrate to null safety
 

pubspec.yaml

diff --git a/pubspec.yaml b/pubspec.yaml
index 42aeede..a59c77d 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -1,14 +1,14 @@
 name: source_maps
-version: 1.0.0-dev
+version: 0.11.0-nullsafety
 
 description: Library to programmatically manipulate source map files.
 homepage: https://github.com/dart-lang/source_maps
 
 environment:
-  sdk: '>=2.9.0-1 <3.0.0'
+  sdk: '>=2.9.0-18.0 <2.9.0'
 
 dependencies:
-  source_span: ^1.5.4
+  source_span: '>=1.8.0-nullsafety <1.8.0'
 
 dev_dependencies:
   test: ^1.2.0
@@ -30,24 +30,16 @@
     git:
       url: git://github.com/dart-lang/charcode.git
       ref: null_safety
-  collection:
-    git:
-      url: git://github.com/dart-lang/collection.git
-      ref: null_safety
+  collection: 1.15.0-nullsafety
   js:
     git:
       url: git://github.com/dart-lang/sdk.git
-      ref: null_safety-pkgs
       path: pkg/js
   matcher:
     git:
       url: git://github.com/dart-lang/matcher.git
       ref: null_safety
-  meta:
-    git:
-      url: git://github.com/dart-lang/sdk.git
-      ref: null_safety-pkgs
-      path: pkg/meta
+  meta: 1.3.0-nullsafety
   path:
     git:
       url: git://github.com/dart-lang/path.git