Make double underscore "__" an error for ES 300, but a warning for 310.

The 310 spec (and desktop specs) have clarified this is a waring, not an
error, but 300 tests still expect an error.

Test/300BuiltIns.frag

@@ -3,7 +3,7 @@
 int imax, imin;
 uint umax, umin;
 
-vec3 x, y;
+vec3 x, y;    // ERROR, needs default precision
 bvec3 bv;
 
 uint uy;
@@ -67,5 +67,10 @@ void main()
     vec2 v18 = unpackHalf2x16(uy);
 
     // not present
-    noise2(v18);
+    noise2(v18);  // ERROR, not present
+
+    float t__;  // ERROR, no __ until revision 310
+
+      // ERROR, no __ until revision 310
+    #define __D
 }

Test/310.comp

@@ -231,3 +231,8 @@ in inb {     // ERROR
 out outb {     // ERROR
     int a;
 } outbi;
+
+float t__;  // ERROR, no __ until revision 310
+
+    // ERROR, no __ until revision 310
+#define __D

Test/baseResults/300BuiltIns.frag.out

@@ -1,7 +1,9 @@
 300BuiltIns.frag
 ERROR: 0:6: 'float' : type requires declaration of default precision qualifier 
 ERROR: 0:70: 'noise2' : no matching overloaded function found 
-ERROR: 2 compilation errors.  No code generated.
+ERROR: 0:72: 't__' : identifiers containing consecutive underscores ("__") are reserved, and an error if version <= 300 
+ERROR: 0:75: '#define' : names containing consecutive underscores are reserved, and an error if version <= 300: __D
+ERROR: 4 compilation errors.  No code generated.
 
 
 Shader version: 300

Test/baseResults/310.comp.out

@@ -74,6 +74,8 @@ ERROR: 0:221: 'assign' : can't read from writeonly object:  wo
 ERROR: 0:222: '~' : can't read from writeonly object:  wo
 ERROR: 0:227: 'input block' : not supported in this stage: compute
 ERROR: 0:231: 'output block' : not supported in this stage: compute
+WARNING: 0:235: 't__' : identifiers containing consecutive underscores ("__") are reserved 
+WARNING: 0:238: '#define' : names containing consecutive underscores are reserved: __D
 ERROR: 74 compilation errors.  No code generated.
 
 
@@ -483,6 +485,7 @@ ERROR: node is still EOpNull!
 0:?     'multio' (layout(column_major shared ) buffer block{layout(column_major shared ) readonly buffer highp int value, layout(column_major shared ) writeonly buffer implicitly-sized array of highp float values})
 0:?     'inbi' (in block{in highp int a})
 0:?     'outbi' (out block{out highp int a})
+0:?     't__' (global highp float)
 
 
 Linked compute stage:
@@ -894,4 +897,5 @@ ERROR: node is still EOpNull!
 0:?     'multio' (layout(column_major shared ) buffer block{layout(column_major shared ) readonly buffer highp int value, layout(column_major shared ) writeonly buffer implicitly-sized array of highp float values})
 0:?     'inbi' (in block{in highp int a})
 0:?     'outbi' (out block{out highp int a})
+0:?     't__' (global highp float)