Make implementations consistent across platforms: ensure IsDirectory and IsFile return false even when the file doesn't exist (and they return an nsresult error status). b=187014 r=dougt sr=alecf

xpcom/io/nsLocalFileOSX.cpp

@@ -963,6 +963,7 @@ NS_IMETHODIMP nsLocalFile::IsHidden(PRBool *_retval)
 NS_IMETHODIMP nsLocalFile::IsDirectory(PRBool *_retval)
 {
   NS_ENSURE_ARG_POINTER(_retval);
+  *_retval = PR_FALSE;
   
   FSRef fsRef;
   nsresult rv = GetFSRefInternal(fsRef);
@@ -982,6 +983,7 @@ NS_IMETHODIMP nsLocalFile::IsDirectory(PRBool *_retval)
 NS_IMETHODIMP nsLocalFile::IsFile(PRBool *_retval)
 {
   NS_ENSURE_ARG_POINTER(_retval);
+  *_retval = PR_FALSE;
   
   FSRef fsRef;
   nsresult rv = GetFSRefInternal(fsRef);

xpcom/io/nsLocalFileUnix.cpp

@@ -1291,6 +1291,7 @@ NS_IMETHODIMP
 nsLocalFile::IsDirectory(PRBool *_retval)
 {
     NS_ENSURE_ARG_POINTER(_retval);
+    *_retval = PR_FALSE;
     VALIDATE_STAT_CACHE();
     *_retval = S_ISDIR(mCachedStat.st_mode);
     return NS_OK;
@@ -1300,6 +1301,7 @@ NS_IMETHODIMP
 nsLocalFile::IsFile(PRBool *_retval)
 {
     NS_ENSURE_ARG_POINTER(_retval);
+    *_retval = PR_FALSE;
     VALIDATE_STAT_CACHE();
     *_retval = S_ISREG(mCachedStat.st_mode);
     return NS_OK;