Revert "[native_stack_traces] Remove initial spaces check in stack trace lines."

This reverts commit ae4ee87.

Reason for revert: Broke integration tests on precompiled bots.

Original change's description:
> [native_stack_traces] Remove initial spaces check in stack trace lines.
>
> The strictness of the old "check for four spaces" was causing failures
> in `flutter symbolize`, and there's no reason to check how much initial
> whitespace we got prior to the line contents anyway.
>
> TEST=pkg/native_stack_traces/test/convert/regress_262474517_test
>
> Change-Id: I6a6e31732cb2a5b5d40a088b9a04877052726be2
> Bug: b/262474517
> Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/276905
> Reviewed-by: Daco Harkes <[email protected]>
> Commit-Queue: Tess Strickland <[email protected]>

[email protected],[email protected],[email protected]

Change-Id: I83bfa2d09570d8ae4d244b987bd5acf855e57306
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: b/262474517
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/277000
Commit-Queue: Alexander Markov <[email protected]>
Auto-Submit: Tess Strickland <[email protected]>
Reviewed-by: Alexander Markov <[email protected]>

Author: sstrickl

pkg/native_stack_traces/CHANGELOG.md

@@ -1,7 +1,3 @@
-## 0.5.4
-
-- Relaxed requirement for spaces before non-symbolic stack trace line.
-
 ## 0.5.3
 
 - Exported more ELF utilities for use in Dart tests.

pkg/native_stack_traces/lib/src/convert.dart

@@ -125,9 +125,9 @@ const _symbolOffsetREString = r'(?<symbol>' +
     constants.isolateSymbolName +
     r')\+(?<offset>(?:0x)?[\da-f]+)';
 final _symbolOffsetRE = RegExp(_symbolOffsetREString);
-final _traceLineRE =
-    RegExp(r'#(\d+) abs (?<absolute>[\da-f]+)(?: virt (?<virtual>[\da-f]+))? '
-        r'(?<rest>.*)$');
+final _traceLineRE = RegExp(
+    r'    #(\d+) abs (?<absolute>[\da-f]+)(?: virt (?<virtual>[\da-f]+))? '
+    r'(?<rest>.*)$');
 
 /// Parses strings of the format <static symbol>+<integer offset>, where
 /// <static symbol> is one of the static symbols used for Dart instruction

pkg/native_stack_traces/pubspec.yaml

@@ -1,5 +1,5 @@
 name: native_stack_traces
-version: 0.5.4
+version: 0.5.3
 description: Utilities for working with non-symbolic stack traces.
 repository: https://github.com/dart-lang/sdk/tree/main/pkg/native_stack_traces
 
@@ -19,4 +19,3 @@ dependencies:
 # See also https://dart.dev/tools/pub/dependencies.
 dev_dependencies:
   lints: any
-  test: any