Re-enable adding intern table to image

Changed intern table to have a stack of tables similarily to
ClassTable. Adding an image intern table adds to the front of the
intern table stack. Also some cleanup.

Bug: 26317072

Change-Id: I7bbf9485b5dbbbf3707fed21e29de3beccfb8705
diff --git a/runtime/runtime.cc b/runtime/runtime.cc
index dfb2877..01f3bbd 100644
--- a/runtime/runtime.cc
+++ b/runtime/runtime.cc
@@ -543,8 +543,7 @@
   // Use !IsAotCompiler so that we get test coverage, tests are never the zygote.
   if (!IsAotCompiler()) {
     ScopedObjectAccess soa(self);
-    std::vector<gc::space::ImageSpace*> image_spaces = heap_->GetBootImageSpaces();
-    for (gc::space::ImageSpace* image_space : image_spaces) {
+    for (gc::space::ImageSpace* image_space : heap_->GetBootImageSpaces()) {
       ATRACE_BEGIN("AddImageStringsToTable");
       GetInternTable()->AddImageStringsToTable(image_space);
       ATRACE_END();