Remove support for Javascript warnings in the VM.

runtime/vm/exceptions.h

Index: runtime/vm/exceptions.h
diff --git a/runtime/vm/exceptions.h b/runtime/vm/exceptions.h
index ada7606427f721b4cf01a8f54cadfe6574c6f731..89f062c06691e0354e638c9ffcfda7adfd9c6626 100644
--- a/runtime/vm/exceptions.h
+++ b/runtime/vm/exceptions.h
@@ -61,8 +61,6 @@ class Exceptions : AllStatic {
     kOutOfMemory,
     kNullThrown,
     kIsolateSpawn,
-    kJavascriptIntegerOverflowError,
-    kJavascriptCompatibilityError,
     kAssertion,
     kCast,
     kType,
@@ -81,7 +79,6 @@ class Exceptions : AllStatic {
                               const Integer& argument_value,
                               intptr_t expected_from,
                               intptr_t expected_to);
-  static void ThrowJavascriptCompatibilityError(const char* msg);
 
   // Returns a RawInstance if the exception is successfully created,
   // otherwise returns a RawError.