fix(compiler): make sourcemaps work in AOT mode

Inlcuded fixes:
- include preamble in generated source map
- always add a mapping for line/col 0 so that the
  generated sourcemap is not sparse
- use a uniue sourceUrl for inline templates even
  in the AOT case

packages/core/test/linker/source_map_integration_node_only_spec.ts

@@ -125,8 +125,10 @@ export function main() {
            compileAndCreateComponent(MyComp);
 
            const sourceMap = getSourceMap('ng:///DynamicTestModule/MyComp.ngfactory.js');
-           expect(sourceMap.sources).toEqual([templateUrl]);
-           expect(sourceMap.sourcesContent).toEqual([template]);
+           expect(sourceMap.sources).toEqual([
+             'ng:///DynamicTestModule/MyComp.ngfactory.js', templateUrl
+           ]);
+           expect(sourceMap.sourcesContent).toEqual([null, template]);
          }));