Fix some editor warnings.

lib/compiler/implementation/ssa/builder.dart

Index: lib/compiler/implementation/ssa/builder.dart
diff --git a/lib/compiler/implementation/ssa/builder.dart b/lib/compiler/implementation/ssa/builder.dart
index 3db36f015377c3dc81b15ec06f066677f520ac86..3662471c257024a917262963a2134e0dc7b46fb7 100644
--- a/lib/compiler/implementation/ssa/builder.dart
+++ b/lib/compiler/implementation/ssa/builder.dart
@@ -696,20 +696,19 @@ interface JumpHandler default JumpHandlerImpl {
 // used as the target of a break, and therefore doesn't need a break
 // handler associated with it.
 class NullJumpHandler implements JumpHandler {
-  const NullJumpHandler();
+  final Compiler compiler;
+  NullJumpHandler(this.compiler);
 
   void generateBreak([LabelElement label]) {
     // TODO(lrn): Need a compiler object and a location. Since label
     // is optional, it may be null so we also need a position.
-    compiler.internalError('generateBreak should not be called',
-                           missingPosition);
+    compiler.internalError('generateBreak should not be called');
   }
 
   void generateContinue([LabelElement label]) {
     // TODO(lrn): Need a compiler object and a location. Since label
     // is optional, it may be null so we also need a position.
-    compiler.internalError('generateContinue should not be called',
-                           missingPosition);
+    compiler.internalError('generateContinue should not be called');
   }
 
   void forEachBreak(Function ignored) { }
@@ -2803,7 +2802,7 @@ class SsaBuilder implements Visitor {
     TargetElement element = elements[node];
     if (element === null || element.statement !== node) {
       // No breaks or continues to this node.
-      return const NullJumpHandler();
+      return new NullJumpHandler(compiler);
     }
     return new JumpHandler(this, element);
   }