Add data-URI support class to dart:core (next to Uri).

runtime/vm/flow_graph_optimizer.cc

Index: runtime/vm/flow_graph_optimizer.cc
diff --git a/runtime/vm/flow_graph_optimizer.cc b/runtime/vm/flow_graph_optimizer.cc
index b2ef8b35edf4f2d903b2fc093202aa0c9b89ad53..8bee936ff342ba02d509e93c266030de0b44c72b 100644
--- a/runtime/vm/flow_graph_optimizer.cc
+++ b/runtime/vm/flow_graph_optimizer.cc
@@ -177,9 +177,6 @@ bool FlowGraphOptimizer::TryCreateICData(InstanceCallInstr* call) {
     // Do not make the instance call megamorphic if the callee needs to decode
     // the calling code sequence to lookup the ic data and verify if a warning
     // has already been issued or not.
-    // TryCreateICData is only invoked if the ic_data target has not been called
-    // yet, so no warning can possibly have been issued.
-    ASSERT(!call->ic_data()->IssuedJSWarning());

[Lasse Reichstein Nielsen, 2015/11/12 11:48:25]

This was hit by standalone/javascript_compatibility_test/{20,21,50,51} - unless
the optimization threshold was raised from 5 to 7 in that test.

[Florian Schneider, 2015/11/12 11:51:10]

The reason you hit this is because the string interpolation function is now
optimized earlier. 

The assert is not valid -- a call that throws a JS compatibility warning error
may have empty IC data, but the IssuedJSWarning flag set.

     if (call->ic_data()->MayCheckForJSWarning()) {
       return false;
     }