Revert "Make the boot image non-debuggable."

We're hitting b/29043547.

bug:28769520

This reverts commit 279ee76a8a972741d423f8f340939fb272bb8f0c.

Change-Id: Ic971e3db1048668bb48d47b1efc2977a4fff533c
diff --git a/dex2oat/dex2oat.cc b/dex2oat/dex2oat.cc
index db26799..cce83f3 100644
--- a/dex2oat/dex2oat.cc
+++ b/dex2oat/dex2oat.cc
@@ -685,6 +685,12 @@
       Usage("Can't have both --image and (--app-image-fd or --app-image-file)");
     }
 
+    if (IsBootImage()) {
+      // We need the boot image to always be debuggable.
+      // TODO: Remove this once we better deal with full frame deoptimization.
+      compiler_options_->debuggable_ = true;
+    }
+
     if (oat_filenames_.empty() && oat_fd_ == -1) {
       Usage("Output must be supplied with either --oat-file or --oat-fd");
     }