From aa92512ac6869a575e48a94e508411ec349fa3eb Mon Sep 17 00:00:00 2001
From: Victor Berchet <victor@suumit.com>
Date: Mon, 10 Oct 2016 09:15:15 -0700
Subject: [PATCH] fix(compiler): properly shim `:host:before` and
 `:host(:before)` (#12171)

fixes #12165
---
 modules/@angular/compiler/src/shadow_css.ts       |  5 ++++-
 modules/@angular/compiler/test/shadow_css_spec.ts | 11 +++++++----
 2 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/modules/@angular/compiler/src/shadow_css.ts b/modules/@angular/compiler/src/shadow_css.ts
index ddc30555e3..c0c1b2c026 100644
--- a/modules/@angular/compiler/src/shadow_css.ts
+++ b/modules/@angular/compiler/src/shadow_css.ts
@@ -381,7 +381,10 @@ export class ShadowCss {
 
     if (_polyfillHostRe.test(selector)) {
       const replaceBy = this.strictStyling ? `[${hostSelector}]` : scopeSelector;
-      return selector.replace(_polyfillHostNoCombinatorRe, (hnc, selector) => selector + replaceBy)
+      return selector
+          .replace(
+              _polyfillHostNoCombinatorRe,
+              (hnc, selector) => selector[0] === ':' ? replaceBy + selector : selector + replaceBy)
           .replace(_polyfillHostRe, replaceBy + ' ');
     }
 
diff --git a/modules/@angular/compiler/test/shadow_css_spec.ts b/modules/@angular/compiler/test/shadow_css_spec.ts
index 6afb87de01..16de7b4657 100644
--- a/modules/@angular/compiler/test/shadow_css_spec.ts
+++ b/modules/@angular/compiler/test/shadow_css_spec.ts
@@ -112,10 +112,8 @@ export function main() {
       it('should handle no context',
          () => { expect(s(':host {}', 'a', 'a-host')).toEqual('[a-host] {}'); });
 
-      it('should handle tag selector', () => {
-        expect(s(':host(ul) {}', 'a', 'a-host')).toEqual('ul[a-host] {}');
-
-      });
+      it('should handle tag selector',
+         () => { expect(s(':host(ul) {}', 'a', 'a-host')).toEqual('ul[a-host] {}'); });
 
       it('should handle class selector',
          () => { expect(s(':host(.x) {}', 'a', 'a-host')).toEqual('.x[a-host] {}'); });
@@ -141,6 +139,11 @@ export function main() {
         expect(s(':host([a="b"],[c=d]) {}', 'a', 'a-host'))
             .toEqual('[a="b"][a-host], [c="d"][a-host] {}');
       });
+
+      it('should handle pseudo selector', () => {
+        expect(s(':host(:before) {}', 'a', 'a-host')).toEqual('[a-host]:before {}');
+        expect(s(':host:before {}', 'a', 'a-host')).toEqual('[a-host]:before {}');
+      });
     });
 
     describe((':host-context'), () => {