Rename fxjse/ to fxjs/ update files to match class names.

This Cl moves the fxjse/ directory to fxjs/ in anticipation of merging in
fpdfsdk/jsapi. In the process the filenames are updated to better match the
class contents. Static methods are moved to anonymous namespaces as possible.

Review-Url: https://codereview.chromium.org/2136213002
diff --git a/fpdfsdk/javascript/cjs_runtime.cpp b/fpdfsdk/javascript/cjs_runtime.cpp
index 88530f7..7eaf145 100644
--- a/fpdfsdk/javascript/cjs_runtime.cpp
+++ b/fpdfsdk/javascript/cjs_runtime.cpp
@@ -31,7 +31,7 @@
 
 #ifdef PDF_ENABLE_XFA
 #include "fpdfsdk/fpdfxfa/include/fpdfxfa_app.h"
-#include "fxjse/include/cfxjse_value.h"
+#include "fxjs/include/cfxjse_value.h"
 #endif  // PDF_ENABLE_XFA
 
 // static