Fixes a crash when entering a negative index with chrome.tabs.move ....

chrome/renderer/resources/json_schema.js

Index: chrome/renderer/resources/json_schema.js
===================================================================
--- chrome/renderer/resources/json_schema.js	(revision 65777)
+++ chrome/renderer/resources/json_schema.js	(working copy)
@@ -380,10 +380,10 @@
  */
 chromeHidden.JSONSchemaValidator.prototype.validateString = function(
     instance, schema, path) {
-  if (schema.minLength && instance.length < schema.minLength)
+  if ('minLength' in schema && instance.length < schema.minLength)
     this.addError(path, "stringMinLength", [schema.minLength]);
 
-  if (schema.maxLength && instance.length > schema.maxLength)
+  if ('maxLength' in schema && instance.length > schema.maxLength)
     this.addError(path, "stringMaxLength", [schema.maxLength]);
 
   if (schema.pattern && !schema.pattern.test(instance))
@@ -405,10 +405,10 @@
       instance == Number.NEGATIVE_INFINITY )
     this.addError(path, "numberFiniteNotNan", [instance]);
 
-  if (schema.minimum && instance < schema.minimum)
+  if ('minimum' in schema && instance < schema.minimum)
     this.addError(path, "numberMinValue", [schema.minimum]);
 
-  if (schema.maximum && instance > schema.maximum)
+  if ('maximum' in schema && instance > schema.maximum)
     this.addError(path, "numberMaxValue", [schema.maximum]);
 
   if (schema.maxDecimal && instance * Math.pow(10, schema.maxDecimal) % 1)