remove unused firstBuildTime parameter in DevFS::update (#144576)

The title says it all. This parameter is unused and serves no apparent purpose.

packages/flutter_tools/lib/src/devfs.dart

@@ -571,7 +571,6 @@ class DevFS {
     DevFSWriter? devFSWriter,
     String? target,
     AssetBundle? bundle,
-    DateTime? firstBuildTime,
     bool bundleFirstUpload = false,
     bool fullRestart = false,
     File? dartPluginRegistrant,

packages/flutter_tools/lib/src/isolated/devfs_web.dart

@@ -873,7 +873,6 @@ class WebDevFS implements DevFS {
     DevFSWriter? devFSWriter,
     String? target,
     AssetBundle? bundle,
-    DateTime? firstBuildTime,
     bool bundleFirstUpload = false,
     bool fullRestart = false,
     String? projectRootPath,

packages/flutter_tools/lib/src/isolated/resident_web_runner.dart

@@ -129,7 +129,6 @@ class ResidentWebRunner extends ResidentRunner {
 
   FlutterDevice? get device => flutterDevices.first;
   final FlutterProject flutterProject;
-  DateTime? firstBuildTime;
 
   // Used with the new compiler to generate a bootstrap file containing plugins
   // and platform initialization.
@@ -241,7 +240,6 @@ class ResidentWebRunner extends ResidentRunner {
     bool enableDevTools = false, // ignored, we don't yet support devtools for web
     String? route,
   }) async {
-    firstBuildTime = DateTime.now();
     final ApplicationPackage? package = await ApplicationPackageFactory.instance!.getPackageForPlatform(
       TargetPlatform.web_javascript,
       buildInfo: debuggingOptions.buildInfo,
@@ -567,7 +565,6 @@ Please provide a valid TCP port (an integer between 0 and 65535, inclusive).
       ),
       target: target,
       bundle: assetBundle,
-      firstBuildTime: firstBuildTime,
       bundleFirstUpload: isFirstUpload,
       generator: device!.generator!,
       fullRestart: fullRestart,

packages/flutter_tools/lib/src/resident_runner.dart

@@ -556,7 +556,6 @@ class FlutterDevice {
     required Uri mainUri,
     String? target,
     AssetBundle? bundle,
-    DateTime? firstBuildTime,
     bool bundleFirstUpload = false,
     bool bundleDirty = false,
     bool fullRestart = false,
@@ -574,7 +573,6 @@ class FlutterDevice {
         mainUri: mainUri,
         target: target,
         bundle: bundle,
-        firstBuildTime: firstBuildTime,
         bundleFirstUpload: bundleFirstUpload,
         generator: generator!,
         fullRestart: fullRestart,

packages/flutter_tools/lib/src/run_hot.dart

@@ -132,8 +132,6 @@ class HotRunner extends ResidentRunner {
 
   final Map<String, List<int>> benchmarkData = <String, List<int>>{};
 
-  DateTime? firstBuildTime;
-
   String? _targetPlatform;
   String? _sdkName;
   bool? _emulator;
@@ -384,7 +382,6 @@ class HotRunner extends ResidentRunner {
 
     final Stopwatch appStartedTimer = Stopwatch()..start();
     final File mainFile = globals.fs.file(mainPath);
-    firstBuildTime = DateTime.now();
 
     Duration totalCompileTime = Duration.zero;
     Duration totalLaunchAppTime = Duration.zero;
@@ -532,7 +529,6 @@ class HotRunner extends ResidentRunner {
         mainUri: entrypointFile.absolute.uri,
         target: target,
         bundle: assetBundle,
-        firstBuildTime: firstBuildTime,
         bundleFirstUpload: isFirstUpload,
         bundleDirty: !isFirstUpload && rebuildBundle,
         fullRestart: fullRestart,

packages/flutter_tools/test/general.shard/hot_shared.dart

@@ -118,7 +118,6 @@ class FakeFlutterDevice extends Fake implements FlutterDevice {
     Uri? mainUri,
     String? target,
     AssetBundle? bundle,
-    DateTime? firstBuildTime,
     bool bundleFirstUpload = false,
     bool bundleDirty = false,
     bool fullRestart = false,

packages/flutter_tools/test/general.shard/resident_runner_helpers.dart

@@ -280,7 +280,6 @@ class FakeFlutterDevice extends Fake implements FlutterDevice {
     required Uri mainUri,
     String? target,
     AssetBundle? bundle,
-    DateTime? firstBuildTime,
     bool bundleFirstUpload = false,
     bool bundleDirty = false,
     bool fullRestart = false,
@@ -518,7 +517,6 @@ class FakeDevFS extends Fake implements DevFS {
     DevFSWriter? devFSWriter,
     String? target,
     AssetBundle? bundle,
-    DateTime? firstBuildTime,
     bool bundleFirstUpload = false,
     bool fullRestart = false,
     String? projectRootPath,

packages/flutter_tools/test/general.shard/resident_web_runner_test.dart

@@ -1562,7 +1562,6 @@ class FakeWebDevFS extends Fake implements WebDevFS {
     DevFSWriter? devFSWriter,
     String? target,
     AssetBundle? bundle,
-    DateTime? firstBuildTime,
     bool bundleFirstUpload = false,
     bool fullRestart = false,
     String? projectRootPath,
@@ -1731,7 +1730,6 @@ class FakeFlutterDevice extends Fake implements FlutterDevice {
     Uri? mainUri,
     String? target,
     AssetBundle? bundle,
-    DateTime? firstBuildTime,
     bool bundleFirstUpload = false,
     bool bundleDirty = false,
     bool fullRestart = false,