Fix bad generate-at-use-site.

sdk/lib/_internal/compiler/implementation/ssa/builder.dart

Index: sdk/lib/_internal/compiler/implementation/ssa/builder.dart
diff --git a/sdk/lib/_internal/compiler/implementation/ssa/builder.dart b/sdk/lib/_internal/compiler/implementation/ssa/builder.dart
index b42ae6af9dff58125321df4620d161b83b7f5af6..3202bdce2f1842838659c62b522a305d4d5f006f 100644
--- a/sdk/lib/_internal/compiler/implementation/ssa/builder.dart
+++ b/sdk/lib/_internal/compiler/implementation/ssa/builder.dart
@@ -885,7 +885,6 @@ class SwitchCaseJumpHandler extends TargetJumpHandler {
  * This class builds SSA nodes for functions represented in AST.
  */
 class SsaBuilder extends ResolvedVisitor {
-  final Compiler compiler;
   final JavaScriptBackend backend;
   final ConstantSystem constantSystem;
   final CodegenWorkItem work;
@@ -964,10 +963,9 @@ class SsaBuilder extends ResolvedVisitor {
   List<HInstruction> stack = <HInstruction>[];
 
   SsaBuilder(JavaScriptBackend backend,
-                    CodegenWorkItem work,
-                    this.nativeEmitter)
+             CodegenWorkItem work,
+             this.nativeEmitter)
     : this.backend = backend,
-      this.compiler = backend.compiler,
       this.constantSystem = backend.constantSystem,
       this.work = work,
       this.rti = backend.rti,