update for the 2.10 dev sdk (#15)

diff --git a/.travis.yml b/.travis.yml
index 0ff7989..4fceea8 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,7 +1,7 @@
 language: dart
 
 dart:
-  - dev
+  - preview/raw/2.10.0-0.2-dev
 
 dart_task:
   - dart_analyzer: --enable-experiment=non-nullable --fatal-warnings --fatal-infos .
@@ -9,12 +9,12 @@
 matrix:
   include:
   # Only validate formatting using the dev release
-  - dart: dev
+  - dart: preview/raw/2.10.0-0.2-dev
     dart_task: dartfmt
 
 # Only building master means that we don't run two builds for each pull request.
 branches:
-  only: [master, null_safety]
+  only: [master]
 
 cache:
  directories:
diff --git a/pubspec.yaml b/pubspec.yaml
index be87ff8..dffa427 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -6,7 +6,64 @@
 homepage: https://github.com/dart-lang/charcode
 
 environment:
-  sdk: '>=2.9.0-18.0 <2.9.0'
+  # This must remain a tight constraint until nnbd is stable
+  sdk: '>=2.10.0-0 <2.10.0'
 
 dev_dependencies:
   pedantic: ^1.0.0
+
+dependency_overrides:
+  async:
+    git: git://github.com/dart-lang/async.git
+  boolean_selector:
+    git: git://github.com/dart-lang/boolean_selector.git
+  charcode:
+    git: git://github.com/dart-lang/charcode.git
+  collection:
+    git: git://github.com/dart-lang/collection.git
+  js:
+    git:
+      url: git://github.com/dart-lang/sdk.git
+      path: pkg/js
+      ref: 2-10-pkgs
+  matcher:
+    git: git://github.com/dart-lang/matcher.git
+  meta:
+    git:
+      url: git://github.com/dart-lang/sdk.git
+      path: pkg/meta
+      ref: 2-10-pkgs
+  path:
+    git: git://github.com/dart-lang/path.git
+  pedantic:
+    git: git://github.com/dart-lang/pedantic.git
+  pool:
+    git: git://github.com/dart-lang/pool.git
+  source_maps:
+    git: git://github.com/dart-lang/source_maps.git
+  source_map_stack_trace:
+    git: git://github.com/dart-lang/source_map_stack_trace.git
+  source_span:
+    git: git://github.com/dart-lang/source_span.git
+  stack_trace:
+    git: git://github.com/dart-lang/stack_trace.git
+  stream_channel:
+    git: git://github.com/dart-lang/stream_channel.git
+  string_scanner:
+    git: git://github.com/dart-lang/string_scanner.git
+  term_glyph:
+    git: git://github.com/dart-lang/term_glyph.git
+  test_api:
+    git:
+      url: git://github.com/dart-lang/test.git
+      path: pkgs/test_api
+  test_core:
+    git:
+      url: git://github.com/dart-lang/test.git
+      path: pkgs/test_core
+  test:
+    git:
+      url: git://github.com/dart-lang/test.git
+      path: pkgs/test
+  typed_data:
+    git: git://github.com/dart-lang/typed_data.git