Use failedAt in more places (ssa)

pkg/compiler/lib/src/ssa/type_builder.dart

Index: pkg/compiler/lib/src/ssa/type_builder.dart
diff --git a/pkg/compiler/lib/src/ssa/type_builder.dart b/pkg/compiler/lib/src/ssa/type_builder.dart
index 11273e409c11df067168f4980f8a7931d4630357..028157a97df7bd9a04c1697166e894a7f4391a21 100644
--- a/pkg/compiler/lib/src/ssa/type_builder.dart
+++ b/pkg/compiler/lib/src/ssa/type_builder.dart
@@ -166,14 +166,15 @@ class TypeBuilder {
   /// This should only be called in assertions.
   bool assertTypeInContext(ResolutionDartType type, [Spannable spannable]) {
     if (builder.compiler.options.useKernel) return true;
-    return invariant(spannable == null ? CURRENT_ELEMENT_SPANNABLE : spannable,
-        () {
-      ClassElement contextClass = DartTypes.getClassContext(type);
-      return contextClass == null ||
-          contextClass == builder.localsHandler.contextClass;
-    },
-        message: "Type '$type' is not valid context of "
-            "${builder.localsHandler.contextClass}.");
+    ClassElement contextClass = DartTypes.getClassContext(type);
+    assert(
+        contextClass == null ||

[Johnni Winther, 2017/06/06 07:41:18]

Assert can take a ()->bool as the first argument. If we rewrite, we avoid
eagerly computing contextClass.

+            contextClass == builder.localsHandler.contextClass,
+        failedAt(
+            spannable ?? CURRENT_ELEMENT_SPANNABLE,
+            "Type '$type' is not valid context of "
+            "${builder.localsHandler.contextClass}."));
+    return true;
   }
 
   HInstruction analyzeTypeArgument(