try to make clearer, and remove unused code

Author: Narretz

src/ng/directive/input.js

@@ -1567,10 +1567,8 @@ function rangeInputType(scope, element, attr, ctrl, $sniffer, $browser) {
 
   if (minAttrType) {
     ctrl.$validators.min = minAttrType === 'min' && supportsRange ?
-      function noopMinValidator() {
-        // Since all browsers set the input to a valid value, we don't need to check validity
-        return true;
-      } :
+      // Since all browsers set the input to a valid value, we don't need to check validity
+      function noopMinValidator() { return true; } :
       // ngMin doesn't set the min attr, so the browser doesn't adjust the input value as setting min would
       function minValidator(modelValue, viewValue) {
         return ctrl.$isEmpty(viewValue) || isUndefined(minVal) || viewValue >= minVal;
@@ -1581,10 +1579,8 @@ function rangeInputType(scope, element, attr, ctrl, $sniffer, $browser) {
 
   if (maxAttrType) {
     ctrl.$validators.max = maxAttrType === 'max' && supportsRange ?
-      function noopMaxValidator() {
-        // Since all browsers set the input to a valid value, we don't need to check validity
-        return true;
-      } :
+      // Since all browsers set the input to a valid value, we don't need to check validity
+      function noopMaxValidator() { return true; } :
       // ngMax doesn't set the max attr, so the browser doesn't adjust the input value as setting max would
       function maxValidator(modelValue, viewValue) {
         return ctrl.$isEmpty(viewValue) || isUndefined(maxVal) || viewValue <= maxVal;
@@ -1593,19 +1589,16 @@ function rangeInputType(scope, element, attr, ctrl, $sniffer, $browser) {
     setInitialValueAndObserver(maxAttrType, 'max', maxChange);
   }
 
-  function setInitialValueAndObserver(attrType, attrName, changeFn) {
-    var initialAttrValue;
-    if (attrType === attrName) {
-      initialAttrValue = attr[attrName];
-      // Set the actual element attribute so that the browser can adjust the value based on
-      // the max value, which might be interpolated
-      element.attr(attrName, initialAttrValue);
+  function setInitialValueAndObserver(actualAttrName, htmlAttrName, changeFn) {
+    // e.g. max === max
+    if (actualAttrName === htmlAttrName) {
+      // interpolated attributes set the attribute value only after a digest, but we need the
+      // attribute value when the input is first rendered, so that the browser can adjust the
+      // input value based on the min/max value
+      element.attr(htmlAttrName, attr[htmlAttrName]);
     }
 
-    // This initalizes the min/max value, so that non-support browsers validate with the correct
-    // values during the initial $render
-    changeFn(initialAttrValue);
-    attr.$observe(attrName, changeFn);
+    attr.$observe(htmlAttrName, changeFn);
   }
 
   function minChange(val) {

test/ng/directive/inputSpec.js

@@ -3108,7 +3108,7 @@ describe('input', function() {
     describe('ngMin', function() {
 
       it('should validate', function() {
-        var inputElm = helper.compileInput('<input type="range" ng-model="value" name="alias" ng-min="20" />');
+        var inputElm = helper.compileInput('<input type="range" ng-model="value" name="alias" ng-min="50" />');
 
         helper.changeInputValueTo('1');
         expect(inputElm).toBeInvalid();