fix(ivy): allow empty cases for ICU expressions

We used to ignore empty strings for optimization purposes, but it turns out that empty strings are also valid values for ICU cases and we shouldn't ignore those.

FW-1290 #resolve

packages/core/src/render3/i18n.ts

@@ -121,7 +121,7 @@ function extractParts(pattern: string): (string | IcuExpression)[] {
         const block = pattern.substring(prevPos, pos);
         if (ICU_BLOCK_REGEXP.test(block)) {
           results.push(parseICUBlock(block));
-        } else if (block) {  // Don't push empty strings
+        } else {
           results.push(block);
         }
 
@@ -138,10 +138,7 @@ function extractParts(pattern: string): (string | IcuExpression)[] {
   }
 
   const substring = pattern.substring(prevPos);
-  if (substring != '') {
-    results.push(substring);
-  }
-
+  results.push(substring);
   return results;
 }
 
@@ -180,7 +177,7 @@ function parseICUBlock(pattern: string): IcuExpression {
     }
 
     const blocks = extractParts(parts[pos++]) as string[];
-    if (blocks.length) {
+    if (cases.length > values.length) {
       values.push(blocks);
     }
   }

packages/core/test/acceptance/i18n_spec.ts

@@ -618,6 +618,13 @@ onlyInIvy('Ivy i18n logic').describe('runtime i18n', () => {
 
       expect(fixture.nativeElement.innerHTML).toContain('at least');
     });
+
+    it('with empty values', () => {
+      const fixture = initWithTemplate(AppComp, `{count, select, 10 {} 20 {twenty} other {other}}`);
+
+      const element = fixture.nativeElement;
+      expect(element).toHaveText('other');
+    });
   });
 
   describe('should support attributes', () => {