If a hex literal has an 'd' of 'f' in it, such as '0xf' or '0xd', the compiler fails with illegal tree structure.

The other hex literals work.  The issue is probably related to using `f` and `d` in float and double literals.

```
    public void testHexCollisionDouble() {
        assertEquals(13, exec("return 0xd"));
    }

    public void testHexCollisionFloat() {
        assertEquals(15, exec("return 0xf"));
    }

    public void testHex() throws Exception {
        for (int i = 0; i <= 15; i++) {
            String hex = Integer.toHexString(i);
            if ("d".equals(hex) || "f".equals(hex)) {
                continue;
            }
            assertEquals(i, exec("return 0x" + hex));
            assertEquals(i, exec("return 0x" + hex.toUpperCase(Locale.ROOT)));
            assertEquals(i, exec("return 0X" + hex));
            assertEquals(i, exec("return 0X" + hex.toUpperCase(Locale.ROOT)));
        }
    }
```
modules/lang-painless/src/main/java/org/elasticsearch/painless/phase/DefaultSemanticAnalysisPhase.java
semanticScope.replicateCondition(userIfElseNode, userElseBlockNode, LastLoop.class);
        visit(userElseBlockNode, semanticScope.newLocalScope());
        if (semanticScope.getCondition(userIfBlockNode, MethodEscape.class)
            && semanticScope.getCondition(userElseBlockNode, MethodEscape.class)) {
            semanticScope.setCondition(userIfElseNode, MethodEscape.class);
        }
        if (semanticScope.getCondition(userIfBlockNode, LoopEscape.class)
            && semanticScope.getCondition(userElseBlockNode, LoopEscape.class)) {
            semanticScope.setCondition(userIfElseNode, LoopEscape.class);
        }
        if (semanticScope.getCondition(userIfBlockNode, AllEscape.class)
            && semanticScope.getCondition(userElseBlockNode, AllEscape.class)) {
            semanticScope.setCondition(userIfElseNode, AllEscape.class);
        }
        if (semanticScope.getCondition(userIfBlockNode, AnyContinue.class)
            || semanticScope.getCondition(userElseBlockNode, AnyContinue.class)) {
            semanticScope.setCondition(userIfElseNode, AnyContinue.class);
        }
        if (semanticScope.getCondition(userIfBlockNode, AnyBreak.class) || semanticScope.getCondition(userElseBlockNode, AnyBreak.class)) {
            semanticScope.setCondition(userIfElseNode, AnyBreak.class);
        }
    }
    /**
     * Visits a while statement with error checking for an extraneous loop.
     * Checks: control flow
     */
    @Override
    public void visitWhile(SWhile userWhileNode, SemanticScope semanticScope) {
        semanticScope = semanticScope.newLocalScope();
        AExpression userConditionNode = userWhileNode.getConditionNode();