[pkg/native_stack_traces] Create stable null safety version.

Also remove assert no longer needed due to null safety.

Cq-Include-Trybots: luci.dart.try:vm-kernel-precomp-linux-product-x64-try,vm-kernel-precomp-linux-release-x64-try
Change-Id: I1b19316801db7cb586d16e6bdc1f00014be93bdb
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/186286
Reviewed-by: Clement Skau <cskau@google.com>
Commit-Queue: Tess Strickland <sstrickl@google.com>

.dart_tool/package_config.json

@@ -11,7 +11,7 @@
     "constraint, update this by running tools/generate_package_config.dart."
   ],
   "configVersion": 2,
-  "generated": "2021-02-22T20:16:11.942470",
+  "generated": "2021-02-23T10:05:38.675159",
   "generator": "tools/generate_package_config.dart",
   "packages": [
     {
@@ -446,7 +446,7 @@
       "name": "native_stack_traces",
       "rootUri": "../pkg/native_stack_traces",
       "packageUri": "lib/",
-      "languageVersion": "2.10"
+      "languageVersion": "2.12"
     },
     {
       "name": "nnbd_migration",

pkg/native_stack_traces/CHANGELOG.md

@@ -1,5 +1,13 @@
 # Changelog
 
+## 0.4.0
+
+- Stable null safe version of package.
+
+## 0.4.0-nullsafety
+
+- Unstable null safe version of package.
+
 ## 0.3.8
 
 - Support columns when present in line number programs.

pkg/native_stack_traces/lib/src/elf.dart

@@ -863,7 +863,6 @@ class Elf {
     if (header == null) return null;
     // At this point, the endianness and wordSize should have been set
     // during ElfHeader.fromReader.
-    assert(reader.endian != null && reader.wordSize != null);
     final programHeader = ProgramHeader.fromReader(reader, header);
     final sectionHeader = SectionHeader.fromReader(reader, header);
     final sections = <SectionHeaderEntry, Section>{};

pkg/native_stack_traces/pubspec.yaml

@@ -1,19 +1,18 @@
 name: native_stack_traces
 description: Utilities for working with non-symbolic stack traces.
-version: 0.4.0-nullsafety
+version: 0.4.0
 
 homepage: https://github.com/dart-lang/sdk/tree/master/pkg/native_stack_traces
 
 environment:
-  # This must remain a tight constraint until nnbd is stable
-  sdk: '>=2.10.0-0 <2.10.0'
+  sdk: '>=2.12.0-0 <3.0.0'
 
 executables:
   decode:
 
 dependencies:
-  args: ^1.6.0
-  path: ^1.8.0-nullsafety
+  args: ^2.0.0
+  path: ^1.8.0
 
 dev_dependencies:
-  pedantic: ^1.9.2
+  pedantic: ^1.10.0