Implement DeclarationMirror.location for all but ParameterMirrors.

runtime/vm/parser.h

Index: runtime/vm/parser.h
diff --git a/runtime/vm/parser.h b/runtime/vm/parser.h
index 326906dfe6216ec7d1e18bdf5c6d066b49c6089d..e5089c4145428f992d0dd0622ee70efa864b1e8d 100644
--- a/runtime/vm/parser.h
+++ b/runtime/vm/parser.h
@@ -208,6 +208,9 @@ class Parser : public ValueObject {
   static void ParseCompilationUnit(const Library& library,
                                    const Script& script);
 
+  static intptr_t FindLibraryDeclarationPosition(const Library& library,
+                                                 const Script& script);
+
   // Parse top level of a class and register all functions/fields.
   static void ParseClass(const Class& cls);
 
@@ -439,6 +442,7 @@ class Parser : public ValueObject {
                                    const String& url);
   void ParseIdentList(GrowableObjectArray* names);
   void ParseLibraryDefinition();
+  intptr_t GetLibraryDeclarationPosition();
   void ParseLibraryName();
   void ParseLibraryImportExport(intptr_t metadata_pos);
   void ParseLibraryPart();