XFA: Update standalone.gypi and .gitignore to match master

R=thestig@chromium.org

Review URL: https://codereview.chromium.org/1394483005 .
diff --git a/.gitignore b/.gitignore
index 93df69f..3014ed6 100644
--- a/.gitignore
+++ b/.gitignore
@@ -3,6 +3,7 @@
 /build/gyp
 /buildtools
 /out
+/testing/corpus
 /testing/gmock
 /testing/gtest
 /v8
diff --git a/build/standalone.gypi b/build/standalone.gypi
index a8818db..c0eaef4 100644
--- a/build/standalone.gypi
+++ b/build/standalone.gypi
@@ -144,6 +144,10 @@
     'cflags': [
       '-Wall',
       '-W',
+      '-Wno-missing-field-initializers',
+      # Code might someday be made clean for -Wsign-compare, but for now
+      # this produces too much noise to be useful.
+      '-Wno-sign-compare',
       '-Wno-unused-parameter',
       '-pthread',
       '-fno-exceptions',