Revert "[vm,aot] Simple unreachable code elimination before type-flow analysis, take 2"

This reverts commit 56991ad.

Reason for revert: broke building Flutter apps in release mode

Original change's description:
> [vm,aot] Simple unreachable code elimination before type-flow analysis, take 2
> 
> This is the relanding of https://dart-review.googlesource.com/c/sdk/+/121500
> with fixes.
> 
> Original CL description:
> 
> This change adds transformation for very early cleanup of unreachable
> code such as code guarded by if statements with constant conditions or
> code used in assert statements when assertions are disabled.
> 
> The advantage of cleaning such code early is that type-flow analysis
> won't be looking at it and TFA-based tree shaker is able to remove
> more code.
> 
> flutter_gallery_total_size -0.5663% (arm), -0.5409% (arm64)
> build_bench_total_size -2.533% (arm), -2.449% (arm64)
> gesture_detector_total_size -4.183% (arm), -4.072% (arm64)
> 
> Change-Id: Ief8ebd0cd828c0e7a847a824f44d2d97a3595b87
> Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/121901
> Reviewed-by: Ryan Macnak <rmacnak@google.com>
> Reviewed-by: Martin Kustermann <kustermann@google.com>
> Commit-Queue: Alexander Markov <alexmarkov@google.com>

TBR=vegorov@google.com,kustermann@google.com,rmacnak@google.com,alexmarkov@google.com

Change-Id: I25fe5d4457bfcc5ee25506810aa7eee01ca1b28a
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/122023
Reviewed-by: Alexander Markov <alexmarkov@google.com>
Commit-Queue: Alexander Markov <alexmarkov@google.com>

Author: alexmarkov

pkg/frontend_server/lib/frontend_server.dart

@@ -441,7 +441,6 @@ class FrontendCompiler implements CompilerInterface {
           aot: options['aot'],
           useGlobalTypeFlowAnalysis: options['tfa'],
           environmentDefines: environmentDefines,
-          enableAsserts: options['enable-asserts'],
           useProtobufTreeShaker: options['protobuf-tree-shaker']));
     }
     if (results.component != null) {

pkg/vm/lib/kernel_front_end.dart

@@ -59,8 +59,6 @@ import 'transformations/type_flow/transformer.dart' as globalTypeFlow
 import 'transformations/obfuscation_prohibitions_annotator.dart'
     as obfuscationProhibitions;
 import 'transformations/call_site_annotator.dart' as call_site_annotator;
-import 'transformations/unreachable_code_elimination.dart'
-    as unreachable_code_elimination;
 
 /// Declare options consumed by [runCompiler].
 void declareCompilerOptions(ArgParser args) {
@@ -219,7 +217,6 @@ Future<int> runCompiler(ArgResults options, String usage) async {
       aot: aot,
       useGlobalTypeFlowAnalysis: tfa,
       environmentDefines: environmentDefines,
-      enableAsserts: enableAsserts,
       genBytecode: genBytecode,
       bytecodeOptions: bytecodeOptions,
       dropAST: dropAST && !splitOutputByPackages,
@@ -288,7 +285,6 @@ Future<KernelCompilationResults> compileToKernel(
     {bool aot: false,
     bool useGlobalTypeFlowAnalysis: false,
     Map<String, String> environmentDefines,
-    bool enableAsserts: true,
     bool genBytecode: false,
     BytecodeOptions bytecodeOptions,
     bool dropAST: false,
@@ -312,7 +308,6 @@ Future<KernelCompilationResults> compileToKernel(
         component,
         useGlobalTypeFlowAnalysis,
         environmentDefines,
-        enableAsserts,
         useProtobufTreeShaker,
         errorDetector);
   }
@@ -367,7 +362,6 @@ Future _runGlobalTransformations(
     Component component,
     bool useGlobalTypeFlowAnalysis,
     Map<String, String> environmentDefines,
-    bool enableAsserts,
     bool useProtobufTreeShaker,
     ErrorDetector errorDetector) async {
   if (errorDetector.hasCompilationErrors) return;
@@ -382,10 +376,6 @@ Future _runGlobalTransformations(
   // when building a platform dill file for VM/JIT case.
   mixin_deduplication.transformComponent(component);
 
-  // Unreachable code elimination transformation should be performed
-  // before type flow analysis so TFA won't take unreachable code into account.
-  unreachable_code_elimination.transformComponent(component, enableAsserts);
-
   if (useGlobalTypeFlowAnalysis) {
     globalTypeFlow.transformComponent(
         compilerOptions.target, coreTypes, component);

pkg/vm/lib/transformations/unreachable_code_elimination.dart

@@ -33,18 +33,15 @@ class TestingVmTarget extends VmTarget {
 }
 
 Future<Component> compileTestCaseToKernelProgram(Uri sourceUri,
-    {Target target,
-    bool enableSuperMixins = false,
-    Map<String, String> environmentDefines}) async {
+    {Target target, bool enableSuperMixins: false}) async {
   final platformKernel =
       computePlatformBinariesLocation().resolve('vm_platform_strong.dill');
   target ??= new TestingVmTarget(new TargetFlags())
     ..enableSuperMixins = enableSuperMixins;
-  environmentDefines ??= <String, String>{};
   final options = new CompilerOptions()
     ..target = target
     ..linkedDependencies = <Uri>[platformKernel]
-    ..environmentDefines = environmentDefines
+    ..environmentDefines = <String, String>{}
     ..onDiagnostic = (DiagnosticMessage message) {
       fail("Compilation error: ${message.plainTextFormatted.join('\n')}");
     };