dart2js: Refactoring, documentation, and a few bugfixes in Namer class.

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

Index: pkg/compiler/lib/src/ssa/builder.dart
diff --git a/pkg/compiler/lib/src/ssa/builder.dart b/pkg/compiler/lib/src/ssa/builder.dart
index 1b10d11747a3667c5634b564ec74b0c223321761..537c2a418e5e15c48f9a9e0f4f4f315c2155f689 100644
--- a/pkg/compiler/lib/src/ssa/builder.dart
+++ b/pkg/compiler/lib/src/ssa/builder.dart
@@ -4088,7 +4088,7 @@ class SsaBuilder extends ResolvedVisitor {
       // TODO(ahe): Creating a string here is unfortunate. It is slow (due to
       // string concatenation in the implementation), and may prevent
       // segmentation of '$'.
-      String substitutionNameString = backend.namer.getNameForRti(cls);
+      String substitutionNameString = backend.namer.getRuntimeTypeName(cls);
       HInstruction substitutionName = graph.addConstantString(
           new ast.LiteralDartString(substitutionNameString), compiler);
       pushInvokeStatic(null,