Remove Compiler.mainApp and Compiler.mainFunction

tests/compiler/dart2js/deferred_not_in_main_test.dart

Index: tests/compiler/dart2js/deferred_not_in_main_test.dart
diff --git a/tests/compiler/dart2js/deferred_not_in_main_test.dart b/tests/compiler/dart2js/deferred_not_in_main_test.dart
index 9e452239e20488df3b0de2545927160d1ffe7d97..17a330b3c625e3ba10dfbcc6e723e25fc47778c4 100644
--- a/tests/compiler/dart2js/deferred_not_in_main_test.dart
+++ b/tests/compiler/dart2js/deferred_not_in_main_test.dart
@@ -25,7 +25,7 @@ void deferredTest1() {
       return compiler.libraryLoader.lookupLibrary(Uri.parse(name));
     }
 
-    var main = compiler.mainFunction;
+    var main = compiler.frontendStrategy.elementEnvironment.mainFunction;
     var outputUnitForElement = compiler.deferredLoadTask.outputUnitForElement;
 
     var mainOutputUnit = compiler.deferredLoadTask.mainOutputUnit;
@@ -48,7 +48,7 @@ void deferredTest2() {
       return compiler.libraryLoader.lookupLibrary(Uri.parse(name));
     }
 
-    var main = compiler.mainFunction;
+    var main = compiler.frontendStrategy.elementEnvironment.mainFunction;
     var outputUnitForElement = compiler.deferredLoadTask.outputUnitForElement;
 
     var mainOutputUnit = compiler.deferredLoadTask.mainOutputUnit;