Restore test-sensitive whitespace to some test cases

Summary: This trailing whitespace is meaningful for these files. Also, exclude test data from linting.

Test Plan: Ran unit tests.

Reviewers: hach-que, joshuaspence

Reviewed By: joshuaspence

Subscribers: epriestley

Differential Revision: https://secure.phabricator.com/D9462

.arclint

@@ -1,7 +1,7 @@
 {
   "exclude": [
     "(^externals/)",
-    "(\\.lint-test$)"
+    "(/__tests__/data/)"
   ],
   "linters": {
     "chmod": {

src/applications/differential/parser/__tests__/data/missing_context.diff

@@ -8,3 +8,4 @@ index a1f7255..b5fb7b8 100644
  fig
 -grape
  honeydew
+

src/applications/differential/parser/__tests__/data/missing_context_2.diff

@@ -9,3 +9,4 @@ index a1f7255..fa84742 100644
 +guava
 +gooseberry
  honeydew
+

src/applications/differential/parser/__tests__/data/missing_context_3.diff

@@ -15,3 +15,4 @@ index bf66874..071dd49 100644
  banana
  grape
 -honeydew
+