Avoid inlining constants that are used via a deferred import.

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

Index: sdk/lib/_internal/compiler/implementation/ssa/nodes.dart
diff --git a/sdk/lib/_internal/compiler/implementation/ssa/nodes.dart b/sdk/lib/_internal/compiler/implementation/ssa/nodes.dart
index c0487207e7d9b256132f501f3a1ceec434aab5dd..a8107f4cf0838ec769b25e6dcfd72be74710295f 100644
--- a/sdk/lib/_internal/compiler/implementation/ssa/nodes.dart
+++ b/sdk/lib/_internal/compiler/implementation/ssa/nodes.dart
@@ -184,6 +184,13 @@ class HGraph {
     return result;
   }
 
+  HConstant addDeferredConstant(Constant constant, PrefixElement prefix,
+                                Compiler compiler) {
+    Constant wrapper = new DeferredConstant(constant, prefix);
+    compiler.deferredLoadTask.registerConstantDeferredUse(wrapper, prefix);
+    return addConstant(wrapper, compiler);
+  }
+
   HConstant addConstantInt(int i, Compiler compiler) {
     return addConstant(compiler.backend.constantSystem.createInt(i), compiler);
   }