Remove code supporting incremental compilation in dart2js

pkg/compiler/lib/src/use_unused_api.dart

Index: pkg/compiler/lib/src/use_unused_api.dart
diff --git a/pkg/compiler/lib/src/use_unused_api.dart b/pkg/compiler/lib/src/use_unused_api.dart
index de79fb6f41ea0320a82001db5d15f00f637a2c3b..af3baf1a35c70c15aba373dbb1cf09b835d0aa01 100644
--- a/pkg/compiler/lib/src/use_unused_api.dart
+++ b/pkg/compiler/lib/src/use_unused_api.dart
@@ -70,9 +70,7 @@ void main(List<String> arguments) {
   useElements();
   useCompiler(null);
   useTypes();
-  useCodeEmitterTask(null);
   useScript(null);
-  useProgramBuilder(null);
   useSemanticVisitor();
   useDeferred();
 }
@@ -283,28 +281,16 @@ useCompiler(compiler.Compiler c) {
     ..reset()
     ..resetAsync(null)
     ..lookupLibrary(null);
-  c.forgetElement(null);
   c.backend.constantCompilerTask.copyConstantValues(null);
   c.currentlyInUserCode();
 }
 
 useTypes() {}
 
-useCodeEmitterTask(js_emitter.CodeEmitterTask codeEmitterTask) {
-  full.Emitter fullEmitter = codeEmitterTask.emitter;
-  fullEmitter.clearCspPrecompiledNodes();
-  fullEmitter.buildLazilyInitializedStaticField(null, isolateProperties: null);
-}
-
 useScript(Script script) {
   script.copyWithFile(null);
 }
 
-useProgramBuilder(program_builder.ProgramBuilder builder) {
-  builder.buildMethodHackForIncrementalCompilation(null);
-  builder.buildFieldsHackForIncrementalCompilation(null);
-}
-
 useSemanticVisitor() {
   operators.UnaryOperator.fromKind(null);
   operators.BinaryOperator.fromKind(null);