fix(limitTo): start at 0 if begin is negative and exceeds input length

Previously, specifying a negative `begin` whose abs value exceeds the
input's length, would behave unexpectedly (depending on the value of
`limit` relative to `begin`). E.g.:

```
limitToFilter('12345', 3, -7) === '1'
// but
limitToFilter('12345', 10, -7) === '123'
```

This commit fixes the unexpected behaviour, by setting `begin` to 0 in the
aforementioned cases. Thus, the previous examples become:

```
limitToFilter('12345', 3, -7) === limitToFilter('12345', 3, 0) === '123'
// and
limitToFilter('12345', 10, -7) === limitToFilter('12345', 10, 0) === '12345'
```

Fixes angular#12775
Closes angular#12781

src/ng/filter/limitTo.js

@@ -111,7 +111,7 @@ function limitToFilter() {
     if (!isArray(input) && !isString(input)) return input;
 
     begin = (!begin || isNaN(begin)) ? 0 : toInt(begin);
-    begin = (begin < 0 && begin >= -input.length) ? input.length + begin : begin;
+    begin = (begin < 0) ? Math.max(0, input.length + begin) : begin;
 
     if (limit >= 0) {
       return input.slice(begin, begin + limit);

test/ng/filter/limitToSpec.js

@@ -140,16 +140,19 @@ describe('Filter: limitTo', function() {
 
   it('should return an empty array if Y exceeds input length', function() {
     expect(limitTo(items, '3', 12)).toEqual([]);
-    expect(limitTo(items, 4, '-12')).toEqual([]);
     expect(limitTo(items, -3, '12')).toEqual([]);
-    expect(limitTo(items, '-4', -12)).toEqual([]);
   });
 
   it('should return an empty string if Y exceeds input length', function() {
     expect(limitTo(str, '3', 12)).toEqual("");
-    expect(limitTo(str, 4, '-12')).toEqual("");
     expect(limitTo(str, -3, '12')).toEqual("");
-    expect(limitTo(str, '-4', -12)).toEqual("");
+  });
+
+  it('should start at 0 if Y is negative and exceeds input length', function() {
+    expect(limitTo(items, 4, '-12')).toEqual(['a', 'b', 'c', 'd']);
+    expect(limitTo(items, '-4', -12)).toEqual(['e', 'f', 'g', 'h']);
+    expect(limitTo(str, 4, '-12')).toEqual("tuvw");
+    expect(limitTo(str, '-4', -12)).toEqual("wxyz");
   });
 
   it('should return the entire string beginning from Y if X is positive and X+Y exceeds input length', function() {