Add a simple tool for isolating a path from an SKP

BUG=skia:

Change-Id: I5ca9bbd43919e3f65ea940847c68f85cc78dfeda
Reviewed-on: https://skia-review.googlesource.com/10130
Commit-Queue: Chris Dalton <csmartdalton@google.com>
Reviewed-by: Jim Van Verth <jvanverth@google.com>
diff --git a/BUILD.gn b/BUILD.gn
index b38f003..41694d3 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -1113,6 +1113,7 @@
               ]
     deps = [
       ":experimental_svg_model",
+      ":flags",
       ":gm",
       ":tool_utils",
       ":views",