Package test fonts on the debug runtime mode. (flutter/engine#3582)

engine/src/flutter/runtime/BUILD.gn

@@ -92,9 +92,10 @@ source_set("runtime") {
 
   defines = []
 
-  if (current_toolchain == host_toolchain) {
+  if (flutter_runtime_mode == "debug" || current_toolchain == host_toolchain) {
     # Though the test font data is small, we dont want to add to the binary size
-    # on the device. We only add the same on the host test shells.
+    # on the device (in profile and release modes). We only add the same on the
+    # host test shells and the debug device shell.
     defines += [ "EMBED_TEST_FONT_DATA=1" ]
   }
 

engine/src/flutter/shell/platform/android/io/flutter/app/FlutterActivity.java

@@ -33,6 +33,9 @@ public class FlutterActivity extends Activity {
         if (intent.getBooleanExtra("start-paused", false)) {
             args.add("--start-paused");
         }
+        if (intent.getBooleanExtra("use-test-fonts", false)) {
+            args.add("--use-test-fonts");
+        }
         if (intent.getBooleanExtra("enable-dart-profiling", false)) {
             args.add("--enable-dart-profiling");
         }