Fix type-checks for reflective redirection constructors.

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 b4048bdb8d3444d0286096947a2b3b11c9ad54e8..109e3df07d4b57b78d3722a7517baba0a9f81472 100644
--- a/sdk/lib/_internal/compiler/implementation/ssa/builder.dart
+++ b/sdk/lib/_internal/compiler/implementation/ssa/builder.dart
@@ -2176,9 +2176,25 @@ class SsaBuilder extends ResolvedVisitor {
             return;
           }
         }
-        HInstruction newParameter = potentiallyCheckType(
-            localsHandler.directLocals[parameterElement],
-            parameterElement.type);
+        HInstruction newParameter =
+            localsHandler.directLocals[parameterElement];
+        if (!element.isConstructor ||
+            !(element as ConstructorElement).isRedirectingFactory) {
+          // Redirection factories must not check their argument types.
+          // Example:
+          //
+          //     class A {
+          //       A(String foo) = A.b;
+          //       A(int foo) { print(foo); }
+          //     }
+          //     main() {
+          //       new A(499);    // valid even in checked mode.
+          //       new A("foo");  // invalid in checked mode.
+          //
+          // Only the final target is allowed to check for the argument types.
+          newParameter =
+              potentiallyCheckType(newParameter, parameterElement.type);
+        }
         localsHandler.directLocals[parameterElement] = newParameter;
       });