Shrink some fields and add some bounds checks.

runtime/vm/object.cc

Index: runtime/vm/object.cc
diff --git a/runtime/vm/object.cc b/runtime/vm/object.cc
index d95d307668ba37b42e9980ae11f4ba5dfb406bae..31a8bfdc1beab180c1317f8e71140bb438589c9d 100644
--- a/runtime/vm/object.cc
+++ b/runtime/vm/object.cc
@@ -8698,6 +8698,25 @@ void LibraryPrefixIterator::Advance() {
 }
 
 
+static void ReportTooManyImports(const Library& lib) {
+  String& url = String::Handle(lib.url());

[siva, 2015/06/09 01:29:02]

const String& url

[rmacnak, 2015/06/09 17:47:11]

Done.

+  Report::MessageF(Report::kError,
+                   Script::Handle(lib.LookupScript(url)),
+                   Scanner::kNoSourcePos,
+                   "too many imports in library '%s'",
+                   url.ToCString());
+  UNREACHABLE();
+}
+
+
+void Library::set_num_imports(intptr_t value) const {
+  if (!Utils::IsUint(16, value)) {
+    ReportTooManyImports(*this);
+  }
+  StoreNonPointer(&raw_ptr()->num_imports_, value);
+}
+
+
 void Library::SetName(const String& name) const {
   // Only set name once.
   ASSERT(!Loaded());
@@ -10294,6 +10313,9 @@ void LibraryPrefix::set_imports(const Array& value) const {
 
 
 void LibraryPrefix::set_num_imports(intptr_t value) const {
+  if (!Utils::IsUint(16, value)) {
+    ReportTooManyImports(Library::Handle(importer()));
+  }
   StoreNonPointer(&raw_ptr()->num_imports_, value);
 }
 
@@ -15568,6 +15590,7 @@ void TypeParameter::set_parameterized_class(const Class& value) const {
 
 void TypeParameter::set_index(intptr_t value) const {
   ASSERT(value >= 0);
+  ASSERT(Utils::IsInt(16, value));
   StoreNonPointer(&raw_ptr()->index_, value);
 }