build: Fix common misspellings

Bug: 750830
Change-Id: Ie4cc9f02e3cc23f0ed3e44b5372745eee9944165
Reviewed-on: https://chromium-review.googlesource.com/594770
Reviewed-by: Scott Graham <[email protected]>
Commit-Queue: Julien Brianceau <[email protected]>
Cr-Commit-Position: refs/heads/master@{#490922}
diff --git a/build/gn_helpers.py b/build/gn_helpers.py
index 33cc578..a9d1e2e 100644
--- a/build/gn_helpers.py
+++ b/build/gn_helpers.py
@@ -182,7 +182,7 @@
 
     - GN strings (double-quoted as in '"asdf"') will be converted to Python
       strings with GN escaping rules. GN string interpolation (embedded
-      variables preceeded by $) are not supported and will be returned as
+      variables preceded by $) are not supported and will be returned as
       literals.
 
     - GN lists ('[1, "asdf", 3]') will be converted to Python lists.