fix: escape unicode characters in css with a double blackslash (#453)

Closes #425

.gitignore

@@ -9,6 +9,9 @@ yarn-error.log*
 /.vs
 /.idea
 
+# IDE files
+*.iml
+
 # Runtime data
 pids
 *.pid

integration/samples/material/baz/baz.component.scss

@@ -2,4 +2,5 @@
 
 .baz {
     color: $variable-defined-by-file-not-processed-by-loader;
+    content: "\2014 \00A0";
 }

integration/samples/material/specs/metadata.ts

@@ -38,6 +38,9 @@ describe(`@sample/material`, () => {
       it(`should have style with: "color: red"`, () => {
         expect(METADATA['metadata'].BazComponent.decorators[0].arguments[0].styles[0]).to.have.string('color: "red"');
       });
+      it(`should have style with: "content: \\2014 \\00A0"`, () => {
+        expect(METADATA['metadata'].BazComponent.decorators[0].arguments[0].styles[0]).to.have.string('content: "\\2014 \\00A0"');
+      });
     });
 
   });

src/lib/steps/assets.ts

@@ -89,6 +89,9 @@ const processStylesheet =
           to: stylesheetFilePath.replace(path.extname(stylesheetFilePath), '.css')
         });
 
+      // Escape existing backslashes for the final output into a string literal, which would otherwise escape the character after it
+      result.css = result.css.replace(/\\/g, '\\\\');
+
       // Log warnings from postcss
       result.warnings().forEach((msg) => {
         log.warn(msg.toString());