Use shared implementation of Stopwatch.

dart/frog/leg/ssa/builder.dart

Index: dart/frog/leg/ssa/builder.dart
diff --git a/dart/frog/leg/ssa/builder.dart b/dart/frog/leg/ssa/builder.dart
index 11b6ef20b360fcebf33a6cca4bd45e0f3be57d82..192ead9bcd266177386e888ee165ae53c73ad0a3 100644
--- a/dart/frog/leg/ssa/builder.dart
+++ b/dart/frog/leg/ssa/builder.dart
@@ -1585,8 +1585,10 @@ class SsaBuilder implements Visitor {
   visitStaticSend(Send node) {
     Selector selector = elements.getSelector(node);
     Element element = elements[node];
-    if (element.kind != ElementKind.FUNCTION &&
-        element.kind != ElementKind.GENERATIVE_CONSTRUCTOR) {
+    if (element.kind === ElementKind.GENERATIVE_CONSTRUCTOR) {
+      compiler.resolver.resolveMethodElement(element);
+      element = element.implementation;
+    } else if (element.kind != ElementKind.FUNCTION) {
       compiler.unimplemented(
           "SsaBuilder.visitStaticSend static field invocation",
           node: node);