Add some mojom.stamp files to public/.gitignore.

This makes it match the copy in the fuchsia mojo repo.

TBR=vardhan@google.com

Review URL: https://codereview.chromium.org/2245073004 .

Cr-Mirrored-From: https://github.com/domokit/mojo
Cr-Mirrored-Commit: d3823ef2b8141c42724a35c69257b0232e133462
diff --git a/.gitignore b/.gitignore
index 031ef3a..f99f2ab 100644
--- a/.gitignore
+++ b/.gitignore
@@ -3,7 +3,9 @@
 
 # Download the Mojom parser binary.
 /tools/bindings/mojom_tool/bin/linux64/mojom
+/tools/bindings/mojom_tool/bin/linux64/mojom.stamp
 /tools/bindings/mojom_tool/bin/mac64/mojom
+/tools/bindings/mojom_tool/bin/mac64/mojom.stamp
 
 # Download the mojom generators.
 # A generator is anything in the generators directory except sha1 files.