src,tools: use template literals

Convert string concatenation to template literals. Enforce with lint
rule.
PR-URL: #5778
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Michaël Zasso <mic.besace@gmail.com>
Reviewed-By: Johan Bergström <bugs@bergstroem.nu>

Author: Trott

src/.eslintrc

@@ -0,0 +1,3 @@
+# ECMAScript-6
+# http://eslint.org/docs/rules/#ecmascript-6
+prefer-template: 2

src/node.js

@@ -564,19 +564,19 @@
 module.paths=Module._nodeModulePaths(cwd);
 varscript=process._eval;
 varbody=script;
-script='global.__filename = '+JSON.stringify(name)+';\n'+
+script=`global.__filename = ${JSON.stringify(name)};\n`+
 'global.exports = exports;\n'+
 'global.module = module;\n'+
 'global.__dirname = __dirname;\n'+
 'global.require = require;\n'+
 'return require("vm").runInThisContext('+
-JSON.stringify(body)+', { filename: '+
-JSON.stringify(name)+' });\n';
+`${JSON.stringify(body)}, { filename: `+
+`${JSON.stringify(name)}});\n`;
 // Defer evaluation for a tick. This is a workaround for deferred
 // events not firing when evaluating scripts from the command line,
 // see https://github.com/nodejs/node/issues/1600.
 process.nextTick(function(){
-varresult=module._compile(script,name+'-wrapper');
+varresult=module._compile(script,`${name}-wrapper`);
 if(process._print_eval)console.log(result);
 });
 }
@@ -768,7 +768,7 @@
 sig.slice(0,3)==='SIG'){
 err=process._kill(pid,startup.lazyConstants()[sig]);
 }else{
-thrownewError('Unknown signal: '+sig);
+thrownewError(`Unknown signal: ${sig}`);
 }
 }
 
@@ -873,7 +873,7 @@
 }
 
 functionNativeModule(id){
-this.filename=id+'.js';
+this.filename=`${id}.js`;
 this.id=id;
 this.exports={};
 this.loaded=false;
@@ -893,10 +893,10 @@
 }
 
 if(!NativeModule.exists(id)){
-thrownewError('No such native module '+id);
+thrownewError(`No such native module ${id}`);
 }
 
-process.moduleLoadList.push('NativeModule '+id);
+process.moduleLoadList.push(`NativeModule ${id}`);
 
 varnativeModule=newNativeModule(id);