prefer_const_declarations on local variables (#14358)

diff --git a/packages/flutter_tools/lib/src/ios/mac.dart b/packages/flutter_tools/lib/src/ios/mac.dart
index b5b126c..eead7f3 100644
--- a/packages/flutter_tools/lib/src/ios/mac.dart
+++ b/packages/flutter_tools/lib/src/ios/mac.dart
@@ -528,14 +528,14 @@
   if (lines.any((String line) => line.contains('path = Flutter/flutter_assets')))
     return true;
 
-  final String l1 = '		3B3967161E833CAA004F5970 /* AppFrameworkInfo.plist in Resources */ = {isa = PBXBuildFile; fileRef = 3B3967151E833CAA004F5970 /* AppFrameworkInfo.plist */; };';
-  final String l2 = '		2D5378261FAA1A9400D5DBA9 /* flutter_assets in Resources */ = {isa = PBXBuildFile; fileRef = 2D5378251FAA1A9400D5DBA9 /* flutter_assets */; };';
-  final String l3 = '		3B3967151E833CAA004F5970 /* AppFrameworkInfo.plist */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text.plist.xml; name = AppFrameworkInfo.plist; path = Flutter/AppFrameworkInfo.plist; sourceTree = "<group>"; };';
-  final String l4 = '		2D5378251FAA1A9400D5DBA9 /* flutter_assets */ = {isa = PBXFileReference; lastKnownFileType = folder; name = flutter_assets; path = Flutter/flutter_assets; sourceTree = SOURCE_ROOT; };';
-  final String l5 = '				3B3967151E833CAA004F5970 /* AppFrameworkInfo.plist */,';
-  final String l6 = '				2D5378251FAA1A9400D5DBA9 /* flutter_assets */,';
-  final String l7 = '				3B3967161E833CAA004F5970 /* AppFrameworkInfo.plist in Resources */,';
-  final String l8 = '				2D5378261FAA1A9400D5DBA9 /* flutter_assets in Resources */,';
+  const String l1 = '		3B3967161E833CAA004F5970 /* AppFrameworkInfo.plist in Resources */ = {isa = PBXBuildFile; fileRef = 3B3967151E833CAA004F5970 /* AppFrameworkInfo.plist */; };';
+  const String l2 = '		2D5378261FAA1A9400D5DBA9 /* flutter_assets in Resources */ = {isa = PBXBuildFile; fileRef = 2D5378251FAA1A9400D5DBA9 /* flutter_assets */; };';
+  const String l3 = '		3B3967151E833CAA004F5970 /* AppFrameworkInfo.plist */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text.plist.xml; name = AppFrameworkInfo.plist; path = Flutter/AppFrameworkInfo.plist; sourceTree = "<group>"; };';
+  const String l4 = '		2D5378251FAA1A9400D5DBA9 /* flutter_assets */ = {isa = PBXFileReference; lastKnownFileType = folder; name = flutter_assets; path = Flutter/flutter_assets; sourceTree = SOURCE_ROOT; };';
+  const String l5 = '				3B3967151E833CAA004F5970 /* AppFrameworkInfo.plist */,';
+  const String l6 = '				2D5378251FAA1A9400D5DBA9 /* flutter_assets */,';
+  const String l7 = '				3B3967161E833CAA004F5970 /* AppFrameworkInfo.plist in Resources */,';
+  const String l8 = '				2D5378261FAA1A9400D5DBA9 /* flutter_assets in Resources */,';
 
 
   printStatus("Upgrading project.pbxproj of $app' to include the "
@@ -561,10 +561,10 @@
   lines.insert(lines.indexOf(l5) + 1, l6);
   lines.insert(lines.indexOf(l7) + 1, l8);
 
-  final String l9 = '		9740EEBB1CF902C7004384FC /* app.flx in Resources */ = {isa = PBXBuildFile; fileRef = 9740EEB71CF902C7004384FC /* app.flx */; };';
-  final String l10 = '		9740EEB71CF902C7004384FC /* app.flx */ = {isa = PBXFileReference; lastKnownFileType = file; name = app.flx; path = Flutter/app.flx; sourceTree = "<group>"; };';
-  final String l11 = '				9740EEB71CF902C7004384FC /* app.flx */,';
-  final String l12 = '				9740EEBB1CF902C7004384FC /* app.flx in Resources */,';
+  const String l9 = '		9740EEBB1CF902C7004384FC /* app.flx in Resources */ = {isa = PBXBuildFile; fileRef = 9740EEB71CF902C7004384FC /* app.flx */; };';
+  const String l10 = '		9740EEB71CF902C7004384FC /* app.flx */ = {isa = PBXFileReference; lastKnownFileType = file; name = app.flx; path = Flutter/app.flx; sourceTree = "<group>"; };';
+  const String l11 = '				9740EEB71CF902C7004384FC /* app.flx */,';
+  const String l12 = '				9740EEBB1CF902C7004384FC /* app.flx in Resources */,';
 
   if (lines.contains(l9)) {
     printStatus('Removing app.flx from project.pbxproj since it has been '