Clear LeakSanitizer's suppression list

We have cleared all the leaks in our code. There is no need for
those suppressions. Plus, most of them are obsolete due to code
refactoring.

Still keep this file around so that suppressions can be added if needed
in the future.

BUG=pdfium:242,pdfium:260

Review-Url: https://codereview.chromium.org/2360743002
diff --git a/tools/lsan/lsan_suppressions.txt b/tools/lsan/lsan_suppressions.txt
index 1a32a9c..b646ab5 100644
--- a/tools/lsan/lsan_suppressions.txt
+++ b/tools/lsan/lsan_suppressions.txt
@@ -10,10 +10,3 @@
 # See https://www.chromium.org/developers/testing/leaksanitizer for syntax.
 
 ################################################################################
-# CJS_Object/CJS_EmbedObj wrapped by v8::Object currently leak. See bug 260.
-# Obvious leaks:
-leak:*FXJS_NewFxDynamicObj*
-
-# CJS_Field CFX_WideString::StringData leaks
-leak:*CJS_Document*getField_static*
-leak:*CJS_EventHandler*OnField*