update for the 2.10 dev sdk (#62)

This is in preparation for the actual 2.10 dev sdk release.
diff --git a/.travis.yml b/.travis.yml
index 27b7cf7..ba73a2a 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,28 +1,28 @@
 language: dart
 
 dart:
- - be/raw/latest
+ - preview/raw/2.10.0-0.2-dev
 
 jobs:
   include:
     - stage: analyze_and_format
       name: "Analyzer"
-      dart: be/raw/latest
+      dart: preview/raw/2.10.0-0.2-dev
       os: linux
       script: dartanalyzer --enable-experiment=non-nullable --fatal-warnings --fatal-infos .
     - stage: analyze_and_format
       name: "Format"
-      dart: be/raw/latest
+      dart: preview/raw/2.10.0-0.2-dev
       os: linux
       script: dartfmt -n --set-exit-if-changed .
     - stage: test
       name: "Vm Tests"
-      dart: be/raw/latest
+      dart: preview/raw/2.10.0-0.2-dev
       os: linux
       script: pub run --enable-experiment=non-nullable test -p vm 
     - stage: test
       name: "Web Tests"
-      dart: be/raw/latest
+      dart: preview/raw/2.10.0-0.2-dev
       os: linux
       script: pub run --enable-experiment=non-nullable test -p chrome
 
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 071d86c..6db0fc0 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,4 +1,4 @@
-## 1.0.0-dev
+## 1.0.0-nullsafety
 
 * Migrate to null safety.
   * This is meant to be mostly non-breaking, for opted in users runtime errors
diff --git a/pubspec.yaml b/pubspec.yaml
index 015ed4c..080836b 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -1,5 +1,5 @@
 name: fixnum
-version: 1.0.0-dev
+version: 1.0.0-nullsafety
 
 description: >-
   Library for 32- and 64-bit signed fixed-width integers with consistent
@@ -10,95 +10,65 @@
 publish_to: none
 
 environment:
-  sdk: '>=2.9.0-1 <3.0.0'
+  # This must remain a tight constraint until nnbd is stable
+  sdk: '>=2.10.0-0 <2.10.0'
 
 dev_dependencies:
   pedantic: ^1.8.0
   test: ^1.2.0
 
 dependency_overrides:
-  test:
+  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/test.git
-      ref: null_safety
-      path: pkgs/test
+      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
-      ref: null_safety
       path: pkgs/test_api
   test_core:
     git:
       url: git://github.com/dart-lang/test.git
-      ref: null_safety
       path: pkgs/test_core
-  async:
+  test:
     git:
-      url: git://github.com/dart-lang/async.git
-      ref: null_safety
-  boolean_selector:
-    git:
-      url: git://github.com/dart-lang/boolean_selector.git
-      ref: null_safety
-  charcode:
-    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
-  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
-  path:
-    git:
-      url: git://github.com/dart-lang/path.git
-      ref: null_safety
-  pedantic:
-    git:
-      url: git://github.com/dart-lang/pedantic.git
-      ref: null_safety
-  pool:
-    git:
-      url: git://github.com/dart-lang/pool.git
-      ref: null_safety
-  source_maps:
-    git:
-      url: git://github.com/dart-lang/source_maps.git
-      ref: null_safety
-  source_map_stack_trace:
-    git:
-      url: git://github.com/dart-lang/source_map_stack_trace.git
-      ref: null_safety
-  source_span:
-    git:
-      url: git://github.com/dart-lang/source_span.git
-      ref: null_safety
-  stack_trace:
-    git:
-      url: git://github.com/dart-lang/stack_trace.git
-      ref: null_safety
-  stream_channel:
-    git:
-      url: git://github.com/dart-lang/stream_channel.git
-      ref: null_safety
-  string_scanner:
-    git:
-      url: git://github.com/dart-lang/string_scanner.git
-      ref: null_safety
-  term_glyph:
-    git:
-      url: git://github.com/dart-lang/term_glyph.git
-      ref: null_safety
+      url: git://github.com/dart-lang/test.git
+      path: pkgs/test
+  typed_data:
+    git: git://github.com/dart-lang/typed_data.git