fix(language-service): remove tsickle dependency

Removes the tsickle dependency added when tsickle was added to the
transform compiler.

Added a test to ensure stray dependencies are not added and no
errors are introduced during module flattening.

packages/language-service/src/locate_symbol.ts

@@ -7,7 +7,7 @@
  */
 
 import {AST, Attribute, BoundDirectivePropertyAst, BoundEventAst, ElementAst, TemplateAst, TemplateAstPath, findNode, tokenReference} from '@angular/compiler';
-import {getExpressionScope} from '@angular/compiler-cli';
+import {getExpressionScope} from '@angular/compiler-cli/src/language_services';
 
 import {TemplateInfo} from './common';
 import {getExpressionSymbol} from './expressions';