Use -f instead of -e.

Test: art script
Change-Id: I6e16df301d41e50aead9ed529361a990d3ee4630
diff --git a/tools/art b/tools/art
index d8c079b..6175992 100644
--- a/tools/art
+++ b/tools/art
@@ -533,7 +533,7 @@
   # It may contain additional modules from TEST_CORE_JARS.
   core_jars_list="core-oj core-libart core-icu4j okhttp bouncycastle apache-xml"
   core_jars_suffix=
-  if [[ -e $ANDROID_ROOT/framework/core-oj-hostdex.jar ]]; then
+  if [[ -f $ANDROID_ROOT/framework/core-oj-hostdex.jar ]]; then
     core_jars_suffix=-hostdex
     core_filenames_dir=$ANDROID_ROOT/framework
     core_locations_dir=$ANDROID_ROOT/framework
@@ -541,7 +541,7 @@
     if [[ ${core_locations_dir:0:${#prefix}} = $prefix ]]; then
       core_locations_dir="${core_locations_dir##$prefix}"
     fi
-  elif [[ -e $ANDROID_ROOT/apex/com.android.art/javalib/core-oj.jar ]]; then
+  elif [[ -f $ANDROID_ROOT/apex/com.android.art/javalib/core-oj.jar ]]; then
     core_jars_suffix=
     core_filenames_dir=$ANDROID_ROOT/apex/com.android.art/javalib
     core_locations_dir=/apex/com.android.art/javalib
@@ -558,7 +558,7 @@
       boot_separator=":"
     done
     # Add conscrypt.
-    if [[ -e $ANDROID_ROOT/framework/conscrypt-hostdex.jar ]]; then
+    if [[ -f $ANDROID_ROOT/framework/conscrypt-hostdex.jar ]]; then
       DEX_FILENAME="conscrypt-hostdex.jar"
       DEX2OAT_BCP+="$boot_separator$core_filenames_dir/${DEX_FILENAME}"
       DEX2OAT_BCP_LOCS+="$boot_separator$core_locations_dir/${DEX_FILENAME}"