Fix bitfield enums to not trigger upcoming Clang warning

Fix bitfield enums to not trigger upcoming Clang warning regarding
non-unsigned enum bitfields producing non-portable code.

For more details, see the patch here: https://reviews.llvm.org/D24289

BUG=648462

Review-Url: https://codereview.chromium.org/2349153002
Cr-Commit-Position: refs/heads/master@{#39649}

src/base/safe_conversions_impl.h

@@ -90,10 +90,10 @@ struct StaticDstRangeRelationToSrcRange<Dst,
   static const NumericRangeRepresentation value = NUMERIC_RANGE_NOT_CONTAINED;
 };
 
-enum RangeConstraint {
-  RANGE_VALID = 0x0,  // Value can be represented by the destination type.
+enum RangeConstraint : unsigned char {
+  RANGE_VALID = 0x0,      // Value can be represented by the destination type.
   RANGE_UNDERFLOW = 0x1,  // Value would overflow.
-  RANGE_OVERFLOW = 0x2,  // Value would underflow.
+  RANGE_OVERFLOW = 0x2,   // Value would underflow.
   RANGE_INVALID = RANGE_UNDERFLOW | RANGE_OVERFLOW  // Invalid (i.e. NaN).
 };
 

src/globals.h

@@ -1058,8 +1058,7 @@ enum InitializationFlag : uint8_t { kNeedsInitialization, kCreatedInitialized };
 enum MaybeAssignedFlag : uint8_t { kNotAssigned, kMaybeAssigned };
 
 // Serialized in PreparseData, so numeric values should not be changed.
-enum ParseErrorType { kSyntaxError = 0, kReferenceError = 1 };
-
+enum ParseErrorType : uint8_t { kSyntaxError = 0, kReferenceError = 1 };
 
 enum MinusZeroMode {
   TREAT_MINUS_ZERO_AS_ZERO,

src/messages.h

@@ -649,7 +649,7 @@ class ErrorUtils : public AllStatic {
 
 class MessageTemplate {
  public:
-  enum Template {
+  enum Template : unsigned {
 #define TEMPLATE(NAME, STRING) k##NAME,
     MESSAGE_TEMPLATES(TEMPLATE)
 #undef TEMPLATE