pdfviewer: add doPage function, cet stream from Contents

experimental/PdfViewer/pdfparser/native/SkNativeParsedPDF.cpp

Index: experimental/PdfViewer/pdfparser/native/SkNativeParsedPDF.cpp
===================================================================
--- experimental/PdfViewer/pdfparser/native/SkNativeParsedPDF.cpp	(revision 10427)
+++ experimental/PdfViewer/pdfparser/native/SkNativeParsedPDF.cpp	(working copy)
@@ -403,7 +403,14 @@
     return fPages.count();
 }
 
+SkPdfPageObjectDictionary* SkNativeParsedPDF::page(int page) {
+    SkASSERT(page >= 0 && page < fPages.count());
+    return fPages[page];
+}
+
+
 SkPdfResourceDictionary* SkNativeParsedPDF::pageResources(int page) {
+    SkASSERT(page >= 0 && page < fPages.count());
     return fPages[page]->Resources(this);
 }
 
@@ -502,8 +509,6 @@
         // TODO(edisonn): generation/updates not supported now
         //int gen = ref->referenceGeneration();
 
-        SkASSERT(!(id < 0 || id > fObjects.count()));
-
         // TODO(edisonn): verify id and gen expected
         if (id < 0 || id >= fObjects.count()) {
             // TODO(edisonn): report error/warning