Lazy implementation of final variables.

lib/compiler/implementation/compiler.dart

Index: lib/compiler/implementation/compiler.dart
diff --git a/lib/compiler/implementation/compiler.dart b/lib/compiler/implementation/compiler.dart
index 1b68df8719f13412a70e87a49c951672b67cbc8f..d753a5997891831555bf945f44ce294b3ca60d13 100644
--- a/lib/compiler/implementation/compiler.dart
+++ b/lib/compiler/implementation/compiler.dart
@@ -719,10 +719,18 @@ class Compiler implements DiagnosticListener {
       progress.reset();
     }
     if (work.element.kind.category == ElementCategory.VARIABLE) {
-      constantHandler.compileWorkItem(work);
-    } else {
-      backend.codegen(work);
+      Constant initialValue = constantHandler.compileWorkItem(work);
+      if (initialValue !== null) {
+        return;
+      } else {
+        // If the constant-handler was not able to produce a result we have to
+        // go through the builder (below) to generate the lazy initializer for
+        // the static variable.
+        // We also need to register the use of the cyclic-error helper.
+        world.registerStaticUse(cyclicThrowHelper);
+      }
     }
+    backend.codegen(work);
   }
 
   void registerInstantiatedClass(ClassElement cls) {
@@ -756,6 +764,18 @@ class Compiler implements DiagnosticListener {
         () => resolver.computeFunctionType(element, signature));
   }
 
+  bool isLazilyInitialized(VariableElement element) {
+    Constant initialValue = compileVariable(element);
+    return initialValue === null;
+  }
+
+  /** Compiles compile-time constants. Must not return `null`. */
+  Constant compileConstant(VariableElement element) {
+    return withCurrentElement(element, () {
+      return constantHandler.compileConstant(element);
+    });
+  }
+
   Constant compileVariable(VariableElement element) {
     return withCurrentElement(element, () {
       return constantHandler.compileVariable(element);
@@ -848,6 +868,10 @@ class Compiler implements DiagnosticListener {
     unimplemented('Compiler.legDirectory');
   }
 
+  Element get cyclicThrowHelper() {
+    return findHelper(const SourceString("throwCyclicInit"));
+  }
+
   Element findHelper(SourceString name)
       => jsHelperLibrary.findLocal(name);
   Element findInterceptor(SourceString name)