Fix bug in InterfaceGenerator.

If a constant name contains words starting with a numeral (e.g DEF_1), 
the InterfaceGenerator generates a method with the constant name in 
camel lower case to access the constant (def1())
The CssRessourceGenerator is not able to match the method with the 
constant afterwards.

Change-Id: I6469b793cc6372b7e0e2dfa2441c1d8779bbb567
Bug-Link: https://github.com/gwtproject/gwt/issues/9401

user/src/com/google/gwt/resources/css/InterfaceGenerator.java

diff --git a/user/src/com/google/gwt/resources/css/InterfaceGenerator.java b/user/src/com/google/gwt/resources/css/InterfaceGenerator.java
index 434cdb3..9e1fa9f 100644
--- a/user/src/com/google/gwt/resources/css/InterfaceGenerator.java
+++ b/user/src/com/google/gwt/resources/css/InterfaceGenerator.java
@@ -306,7 +306,21 @@
     return Lists.newArrayList(Iterables.transform(constantsNames, new Function<String, String>() {
       @Override
       public String apply(String constantName) {
-        return CaseFormat.UPPER_UNDERSCORE.to(CaseFormat.LOWER_CAMEL, constantName);
+        String lowerCase = CaseFormat.UPPER_UNDERSCORE.to(CaseFormat.LOWER_CAMEL, constantName);
+
+        // If we cannot revert the method name to the original constant name, use the
+        // original constant name.
+        // This case happens when number are used after an underscore:
+        // CaseFormat.UPPER_UNDERSCORE.to(CaseFormat.LOWER_CAMEL, "DEF_1") returns def1
+        // but CaseFormat.LOWER_CAMEL.to(CaseFormat.UPPER_UNDERSCORE, "def1") returns DEF1 and the
+        // GssResourceGenerator is not able to match the name of the method with the name of the
+        // constant .
+        if (!constantName.equals(CaseFormat.LOWER_CAMEL.to(CaseFormat.UPPER_UNDERSCORE,
+            lowerCase))) {
+          return constantName;
+        }
+
+        return lowerCase;
       }
     }));
   }