Fix path to d8 and properly quote strings so it works with dash(1)

tools/linux-tick-processor

 #!/bin/sh
 
 # find the name of the log file to process, it must not start with a dash.
 log_file="v8.log"
 for arg in "$@"
 do
   if ! expr "X${arg}" : "^X-" > /dev/null; then
     log_file=${arg}
   fi
 done
 
 tools_path=`cd $(dirname "$0");pwd`
 if [ ! "$D8_PATH" ]; then
   d8_public=`which d8`
-  if [ -x $d8_public ]; then D8_PATH=$(dirname "$d8_public"); fi
+  if [ -x "$d8_public" ]; then D8_PATH=$(dirname "$d8_public"); fi
 fi
-[ "$D8_PATH" ] || D8_PATH=$tools_path/..
+[ -n "$D8_PATH" ] || D8_PATH=$tools_path/..
 d8_exec=$D8_PATH/d8
 
-if [ ! -x $d8_exec ]; then
+if [ ! -x "$d8_exec" ]; then
   D8_PATH=`pwd`/out/native
   d8_exec=$D8_PATH/d8
 fi
 
-if [ ! -x $d8_exec ]; then
+if [ ! -x "$d8_exec" ]; then
   d8_exec=`grep -m 1 -o '".*/d8"' $log_file | sed 's/"//g'`
 fi
 
-if [ ! -x $d8_exec ]; then
+if [ ! -x "$d8_exec" ]; then
   echo "d8 shell not found in $D8_PATH"
   echo "To build, execute 'make native' from the V8 directory"
   exit 1
 fi
 
 # nm spits out 'no symbols found' messages to stderr.
 cat $log_file | $d8_exec $tools_path/splaytree.js $tools_path/codemap.js \
   $tools_path/csvparser.js $tools_path/consarray.js \
   $tools_path/profile.js $tools_path/profile_view.js \
   $tools_path/logreader.js $tools_path/tickprocessor.js \
   $tools_path/tickprocessor-driver.js -- $@ 2>/dev/null