fix(input): fix step validation for input[type=number/range]

Previously, the validation would incorrectly fail in certain cases, due to
Floating Point Arithmetic limitations. The previous fix for FPA limitations
(081d06f) tried to solve the issue by converting the numbers to integers,
before doing the actual calculation, but it failed to acount for cases where the
conversion returned non-integer (again due to FPA limitations).
This commit fixes it by ensuring that the values used in the final calculation
are always integers.

Fixes angular#15504

Author: gkalpak

src/ng/directive/input.js

@@ -1565,15 +1565,27 @@ function isValidForStep(viewValue, stepBase, step) {
   // and `viewValue` is expected to be a valid stringified number.
   var value = Number(viewValue);
 
+  var isNonIntegerValue = !isNumberInteger(value);
+  var isNonIntegerStepBase = !isNumberInteger(stepBase);
+  var isNonIntegerStep = !isNumberInteger(step);
+
   // Due to limitations in Floating Point Arithmetic (e.g. `0.3 - 0.2 !== 0.1` or
   // `0.5 % 0.1 !== 0`), we need to convert all numbers to integers.
-  if (!isNumberInteger(value) || !isNumberInteger(stepBase) || !isNumberInteger(step)) {
-    var decimalCount = Math.max(countDecimals(value), countDecimals(stepBase), countDecimals(step));
+  if (isNonIntegerValue || isNonIntegerStepBase || isNonIntegerStep) {
+    var valueDecimals = isNonIntegerValue ? countDecimals(value) : 0;
+    var stepBaseDecimals = isNonIntegerStepBase ? countDecimals(stepBase) : 0;
+    var stepDecimals = isNonIntegerStep ? countDecimals(step) : 0;
+
+    var decimalCount = Math.max(valueDecimals, stepBaseDecimals, stepDecimals);
     var multiplier = Math.pow(10, decimalCount);
 
     value = value * multiplier;
     stepBase = stepBase * multiplier;
     step = step * multiplier;
+
+    if (isNonIntegerValue) value = Math.round(value);
+    if (isNonIntegerStepBase) stepBase = Math.round(stepBase);
+    if (isNonIntegerStep) step = Math.round(step);
   }
 
   return (value - stepBase) % step === 0;

test/ng/directive/inputSpec.js

@@ -2787,6 +2787,13 @@ describe('input', function() {
             helper.changeInputValueTo('3.5');
             expect(inputElm).toBeValid();
             expect($rootScope.value).toBe(3.5);
+
+            // 1.16 % 0.01 === 0.009999999999999896
+            // 1.16 * 100  === 115.99999999999999
+            $rootScope.step = 0.01;
+            helper.changeInputValueTo('1.16');
+            expect(inputElm).toBeValid();
+            expect($rootScope.value).toBe(1.16);
           }
         );
       });
@@ -3681,6 +3688,13 @@ describe('input', function() {
             helper.changeInputValueTo('3.5');
             expect(inputElm).toBeValid();
             expect($rootScope.value).toBe(3.5);
+
+            // 1.16 % 0.01 === 0.009999999999999896
+            // 1.16 * 100  === 115.99999999999999
+            $rootScope.step = 0.01;
+            helper.changeInputValueTo('1.16');
+            expect(inputElm).toBeValid();
+            expect($rootScope.value).toBe(1.16);
           }
         );
       }